Desktop Power Supply From A Pc

Contents

Desktop Power Supply from a PC Updated March 13, 2009 (See the narrative and disclaimer at the bottom of the page)

Do you have an interest in converting one of these:

into one of these:

A completed 145 watt ATX power supply with switch, binding posts, labels and feet. Notice the zip ties in the ventilation slots

that hold the load resistor.

If you find building your own desktop powersupply from a recycled PSU and a few parts from the local electronics store appealing, then grab some tools, pour yourself a cup of coffee (or personal preference) and let's get started. The LED (light emitting diode) was also salvaged from an old PC. If you want to add a power on indicator, LED's add a nice touch and can easily be wired into the +5v rail. I do strongly encourge you to read the contents of this site and associated links before beginning your conversion -- there are a number of hints included in the associated pages.

This ATX PS board has leads for +5 (RED), -5 (WHITE), +12 (YELLOW), -12 (BLUE) volts, Ground (BLACK) and switch (GREEN). Be warned that some DELL power supplies manufactured between 1996 and 2000 do not follow the industry standard pinout and color codes. The fan has also been unplugged for better viewing. Since this PS was converted for use in the logic and robotics labs, the selected voltages were tapped. Other users may want combinations of +3.3 V (ORANGE), +5 V and/or +12 V if they are converting one of the newer supplies. For R/C applications, the 5 volt output can also serve as a desktop source to

drive receivers and servos. If used as a power source for the micro and sub-micro servos, you must be careful not to drive the servo to either endpoint to avoid stripping the smaller gears in these units. Most standard servos have sufficiently robust gear trains and will simply stall if pushed to the mechanical stops.. Measured voltages on this particular PS (1996 P5-100 MHz Gateway) were about 5.15 and 11.75 volts. The remaining leads have been clipped off at the circuit board.

View of the case top with fan, binding posts and switch. The switch (SPST) and binding posts are available at Radio Shack or other electronics suppliers.

Power supplies in today's computers are known as SWITCHMODE or Switching Mode power supplies and require a load to continue to operate after being switched on (the term switching mode actually applies to the technique of A/C to D/C conversion and not to the

power up action). This load is provided by a 10 watt, 10 ohm wire wound load resistor (sandbar - about $0.80 at Radio Shack) across the +5 volt supply. While many of the newer power supplies will Latch_On without a preload, you will find that adding the resistor will (1) increase the measured voltage on the 12 volt rail slightly and (2) help stabilize the voltage level in this rail by minimizing voltage drop when the powersupply is loaded with a charger. Some inexpensive power supplies may fail if forced on without a load although the Design Guide states that the supplies should not be damaged if run without a sufficient load. The sandbar resistor has been zip tied to the case with a small amount of heat sink compound applied to the flattest side of the resistor . I will also take a file and remove any stamping flash that may remain around the ventilation slots. Without cooling, the resistor will get very hot and may fail prematurely; with this arrangement, the resistor will remain barely warm to the touch. Be warned that many of the heat sink greases can be quite toxic and any excess should be cleaned up and disposed of properly. Also be sure to thoroughly clean your hands and tools after use. While most heatsink compounds are rated to 160 to 170 C, some may dry out over time and their effectiveness will diminish -- a periodic check for good contact between the case and resistor is a recommended practice.

Additional comments

Disclaimer: The information presented should not be considered a "HOWTO" article, but merely a documentation of my conversion process. Modern PC Power Supplies can produce high output current levels that may cause internal overheating in the PS or damage to devices connected to them. Any individual attempting their own conversion is cautioned to carefully research their PS specifications and to be mindful of the associated voltages and power. DO NOT work on your opened power supply with it plugged in!!!! The PS in the picture is a 145 watt ATX salvaged from a 1996 P5-100 MHz Gateway -- I salvage all usable parts from the older PC's before dumping them. This one is set up for a logic lab, hence the +5, -5, +12, -12 volt taps. We also use the +5 to drive servos in the robotics lab. This supply does not have a 3.3 V source, but the newer supplies do. INTEL has continued to modify the ATX specifications to include additional power connectors to support the increased power requirements of the newer motherboards. Before any modification is attempted, you should be sure of the type of power supply you are working with and the output currents being produced at each voltage level. Higher wattage supplies can generate fairly hefty levels of current and may overheat or damage devices attached to them. See the Table of Representative Current Levels for other power supplies. Wiring coming off an industry standard circuit board will be: ORANGE YELLOW BLUE

+3.3 V +12 V -12 V

RED WHITE BLACK GREEN GRAY PURPLE BROWN

+5 V -5 V (May not be present on recently manufactured supplies) GND POWER-ON (Active high -- must be shorted to ground to force power up) POWER-OK What is this?? +5 V STANDBY +3.3 V REMOTE SENSING Design Guide Update

*** Note that the 1996-2000 Dell's did not completely follow this color coding -- check your voltage levels with a meter before wiring *** The yellow, red and black wires will likely be grouped together with a clip. Some of the PS's will have a detachable plug for the fan and some will have the fan permanently attached to the circuit board. If the fan is attached, I usually clip the wires then re-solder and cover with heatshrink tubing -- this gives more working room while modifying the PS and allows me to lube the fan. If you are going to use only the +12v and +5v, you may clip the other wires at the circuit board level or leave the unused wires about an inch long, gather common colors together, slip a piece of heatshrink tubing over the bundle and shrink -- it is an easy way to corral and insulate loose ends. For the +5 / +12 volt PS, you will need the following combinations: Power on Switch (Use a SPST switch; a momentary switch will not work) Pre-Load Resistor (See text for recommended values RED / BLACK and a possible substitution) YELLOW / BLACK +12 volt source RED / BLACK +5 volt source ORANGE / BROWN See the Design Guide Update GREEN / BLACK

I use a single common post (GND -- black) for all voltage sources. Our loads are light and we don't require separate grounds for each. Leave 3 black wires -- switch, load resistor and common (GND) binding post Leave 2 red wires -- 5 volt binding post and load resistor Leave 1 yellow wire -- 12 volt binding post Leave the green wire -- power on switch If sense wires are present, refer to the Design Guide Update

If you expect to place high current demands on your powersupply, it may be prudent to run two wires to each binding post -- while it is very unlikely that the 18 AWG wire will overheat, there have been some instances of melted wires and connectors occurring on high demand motherboards. Cut everything else off even with the board or bundle together as noted above. I usually cut the power harnesses so I can keep as much together as possible. The wires remaining in the power supply should be left long and cut to length as needed. If you leave them too long, they will get in the way when boxing it up, especially if the fan is internal rather than external. Be sure that they stay out of the way of the fan blades. Wire in your power switch between the green (PS_ON) rail and any DC ground (black). The switch (single pole, single throw) and binding posts can be found at local electronics supply houses or online. If your powersupply has a master switch, usually located near the AC plug, you may simply solder the green PS_ON directly to DC ground and use the master switch to power up. This works just as well and will save you the expense of a switch and time needed to install it. Install the 10 ohm 10 watt pre-load resistor between DC ground and the +5V rail (red). Don't forget to heatsink this resistor. Attach your other rails, DC ground, +12v, and +5v if used, to the appropriate binding posts. These posts must not be grounded to the powersupply case, so be sure to check for any continuity between the case and post before trying to powerup the supply. If you want to add a power on indicator light, now's the time to do it. LEDs are quite inexpensive, have incredibly long lifetimes if run at 20 ma or less, produce essentially no heat and can be wired to the +5v rail. However, LEDs are current driven devices and will require a dropping resistor to ensure that it does not burn out immediately. A 1/4 watt carbon film resistor rated at 180 to 220 ohms wired between either of the leads and the PSU will work nicely. LEDs, being a diode, are also polarized and must be wired with the positive lead (anode) attached to +5v rail and the negative lead (cathode) attached to DC ground. LEDs have a flat molded into one side of the base --- this flat will be on the same side as the cathode. If your LED is new and has not had the leads shortened, the longest leg will be the positive lead or anode, but locating the flat is the safest means of determining polarity. Although commercial mounting clips are available, a 3/16" ID rubber grommet works out just as well. Drill your case to accept the grommet, pop it into place and push the LED in until the base bottoms out against the grommet. It will protrude about 1/8" for good visibility. I prefer diffuse lens to clear since they show up better when viewed from the side, but either lens style will add a little DIY pizzazz. When reassembling the case, be sure to reattach the fan -- some supplies will not function without the fan attached - in any event, you need the cooling. This PS in the pictures has the fan mounted on rubber shock mounts and is extremely quiet. I will also disassemble the fan and lube the bearings while I have the PS open. Since these are salvaged, the fans have been in use for some time and normally the bearings are dry -- I use a high grade sewing machine oil from SINGER. Any light oil will work, just don't use WD40 -As an aside, you can get 7 volts from the +5 V and +12 V outputs -- the +5 V is considered

the negative (GND) and +12 the positive -- some geeks will use this combination to run their fans at a lower speed to reduce noise.

I've followed all the instructions, but the output voltage on the +12 V side is still low -- what can I do?? Many of the R/C folks are converting power supplies for the purpose of driving field chargers and are finding that voltage levels below 12 volts are sometimes insufficient to power their chargers. Read these TIPS for some options that may help increase this voltage level, provide a little theory, identify the connector pinouts found on most PC supplies and give a few troubleshooting hints. Is there any way I can get more amperage out of my converted PSU? Updated: March 13, 2009

Improvements in battery technology, brushless motors and more robust speed controllers have allowed "electrics" to expand into model sizes that were once the province of nitro and gas engines only. Obviously, as the motors became more powerful, the batteries required to drive these motors also increased in capacity, measured by the amperage they are able to supply to the flight system. To realize a reasonable charge time, modern battery chargers must be able to deliver more current to these batteries than ever before. In the electronics environment, as in all other closed systems, there ain't no free lunch. Consequently, the chargers also need a higher amperage power source than previously required. Converted PC power supplies may be stretched to the limit by these demands for more current. Is there anything that can be done to squeeze more amps from one of these PSU's? There may be a possible fix to this problem, but your PSU must be one of the newer ATX12V models for you to be able to apply the modification. Visit this page to see if a solution is available for your conversion. Resistor Substitute A viable alternative to using a power resistor is to substitute an 1157 automotive signal lamp in its place. This is a dual filament lamp and its load, with both filaments powered, is usually sufficient to maintain Latch_On and to raise the voltage on the 12v rail to an appropriate level for most needs. Your options are to solder a 5v line (red) to both positive pins on the lamp and ground the base to DC ground or to pick up a twist-lock socket when you buy the lamp. The advantage of using a socket is the ease of replacement should the lamp fail. If you don't feel comfortable with your soldering skills, it is also a little easier to work with the wiring on the socket rather than the pins on the lamp. Just remember that the socket housing is the ground and the two wires in the base are to be attached to the 5v rail. More importantly, you must be very careful that neither the bulb base nor socket housing touch any of the internal components in the power supply. These lamps may be purchased at any automotive supply store and most Walmarts. I prefer the use of resistors since the final converted product is wholly self-contained and I have more control over the applied load, but the use of a lamp does simplify finding and installing components. It also makes a very obvious Power_On indicator!

I usually deal with on-line suppliers such as Jameco, Digikey, Mouser, etc. because we are buying in larger quantities and Radio Shack is too expensive for large numbers of items. However, you should be able to convert your PC supply for $5.00 or $6.00 dollars -- less if you have a junk box of parts. I suppose you could add an LED indicator with a 220 ohm dropping resistor to the 5v rail to show the PS is turned on, but the fan is a pretty good hint. We have had supplies running 24/7 for months without problems -- just electricity consumption. The PS has some fairly hefty electrolytic capacitors and can still give a bit of a shock immediately after being unplugged -- let it sit a couple of minutes before poking around inside. Obviously, you can get whacked if you are inside the case with it still plugged in -probably won't kill you, but you WILL turn it loose (never mind how I discovered this bit of information). If you have any questions, comments or corrections, feel free to mail me.

Remote Sensing ATX Design Changes As one might expect with an ever changing technology, component specifications and modifications represent an ongoing development process. The operation of the microcomputer power supply, while not dictated by INTEL, is nonetheless heavily influenced by the largest player in the motherboard chipset market. INTEL publishes a design guide specification for power supplies to ensure they will be compatible with the most recent chipset offerings and regularly revises this guide as PC power needs change. Revisions may occur as frequently as twice a year and power supply manufacturers must likewise modify their designs to remain current. While manufacturers will advertise their power supplies as meeting ATX12V 2.2 compliance standards -- this may or may not always be the case as some suppliers may be in partial, but not full compliance. INTEL does state that not all ATX12V supplies must conform exactly to their specification. The major changes that have been recently implemented are summarized below: • • • • • •

Remove guidance and reference to the -5 VDC rail Increase the +12 VDC output capability Increase minimum measured efficiency Replace the 2x10 main power connector with a 2x12 connector to support the 75 watt PCI Express requirements Assign a separate current limit for the 12V2 rail and specify a 2x2 connector Add remote sensing to the +3.3 VDC output to compensate for excessive cable drops

The industry standard color coding remains the same with two additions: If your supply is equipped with the higher current rated 12V2 rail, the color coding for this will be yellow with a black stripe and will terminate in a 2x2 keyed MOLEX connector.

The second addition is of more importance to individuals converting their power supplies. The +3.3 VDC remote sensing wire (brown or orange) is connected directly to the orange +3.3 VDC at pin 11 of the power connector (pin 13 if a 2x12). The sense wire will usually be of a lighter gauge (22 AWG) than the power wires (16 or 18 AWG) and its purpose is to monitor the voltage at the connector in order to provide feedback for voltage compensation by the supply. If your PS has two wires attached to the same pin on the motherboard power connector, orange +3.3 VDC and a brown sense wire on Pin 11 for example, then these two wires should be joined when you make your conversion. Some power supplies may also have sense wires running to the +5 VDC and +12 VDC connector pins. If there are multiple sense wires, then they will usually be of the same color as the primary supply wire, but of a lighter wire gauge. These sense wires will also terminate in a different location on the PS printed circuit board than the heavier supply lines. As with the +3.3 sense wire, these additional wires should also be connected to the corresponding supply lines. Failure to complete these connections may result in your power supply not latching into a Power_On mode when switched on. BACK

Mouse over the plugs for pinouts and voltages (Allow time for image to load on slow links)

Keep in mind that power is measured in WATTS and that an increase in power consumption implies there has been an increase in WATTAGE. If a resistor is used to add a load to a circuit, the power consumed will result in heat in the resistor and heat dissipation can become a problem. If the power level becomes too high (resistors are manufactured with a stated resistance (OHMs) and WATTAGE capacity), it may result in an alteration of the internal resistance or, in the worst case, the resistor burning out. Power (watts) is calculated as P = V2 / R. Thus, increases in the power level may be accomplished by increasing the voltage or by reducing the resistance. Higher voltage levels certainly would seem intuitively reasonable, but REDUCING THE RESISTANCE to raise power comsumption??!! AAAARRRRRRRGGGGGHHHHH -- This is too much like school, just tell me what to do!!!

If I wanted to increase the load in a circuit, wouldn't it seem more feasible to increase the resistance? This seeming paradox may be better explained by looking at the extremes. By definition, a resistor restricts the electron flow through the circuit. If we can reduce the electron flow, we can also reduce the amount of work being performed over a period of time. A high level of resistance allows only a small number of electrons to migrate -- materials with extremely high resistance levels are known simply as insulators -- glass, air, rubber, plastic, etc. If I inserted a piece of glass into my circuit and attached the battery leads to each end, nothing would happen -- high resistance, no electron movement, no load and no heat. On the other hand, materials with very low resistance are known as conductors; the lower the resistance, the better the conductor -- silver, copper, gold, aluminum. Placing a thin silver wire across my battery leads might result in the wire beginning to glow or burning completely in two, depending of course on the battery capacity. Hence, low resistance leads to high electron flow, high load and possibly high heat generation. The physics of heat generation is enmeshed in free electron flow, valence shell electrons and other factors that will remain outside this discussion. It is suffice to say that using a resistor with a lower resistance rating will add a greater load to the circuit and produce increasingly higher levels of heat, either within the resistor itself or in other parts of the circuit. Many within the R/C community have been converting power supplies to drive their field chargers, but have not been satisfied with the measured voltage on the +12 V output -- in several cases, the voltage levels have been lower than expected leading to long charge times, power supply shutdowns or charger malfunctions. Relying on a little help from Mr. Ohm, Watt and Kirchhoff, we may be able to increase the amount of work expected from our PC power supply, and in turn, get it to step up to the plate with an increased voltage level. The ATX switching mode power supplies require a static load to function and for many, a 10 ohm 10 watt resistor on the +5 V output is sufficient, but voltage levels on the +12 V line may fall in the range of 11.5 to 11.75 volts, adequate for logic labs, but below desired levels for chargers. Five volt output generally holds around 5.09 to 5.15 volts. Returning to our power calculation, a 10 ohm load across 5.15 volts consumes about 2.65 watts of energy. P = V2 / R = 5.152 / 10 ~ 2.65 watts. By virtue of being a regulated power supply, we cannot easily change the voltage levels -- the ATX power supply design guide specifies a +/- 5% variation for the 3.3, 5 and 12 volt outputs and the internal circuitry is designed to maintain output within those specifications. Consequently, to increase the perceived load, the most easily controlled variable is resistance. If we replace the 10 ohm resistor with a 2 ohm resistor, what change can we expect in the load? As before, P = V2 / R = 5.152 / 2 ~ 13.26 watts. This substitution has certainly increased the load, but it has also introduced another potentially destructive situation. The load resistor must now dissipate this increased energy and it does so in the form of heat. We can deal with heat to some extent, but when the load exceeds the rating of the resistor, our best efforts may not save a 10 watt resistor carrying a continuous 13 watt load. My options are to find a whopper of a resistor with a high load rating or come up with a workable solution using easily obtainable components. Four laws will help us ramp up the perceived load and use off-the-shelf parts to successfully implement them. 1. The total resistance in a SERIES circuit equals the sum of the individual resistances: Rtotal =

R1 + R2 + ... + Rn 2. The sum of voltage drops in a series circuit will equal the voltage source: Vs = Vd1 + Vd2 + ... + Vdn 3. The voltage drop across a resistor in a series circuit is directly proportional to the size (Ohm rating) of the resistor: Vd1 = Vs x R1 / Rtotal 4. The total power consumed in a series circuit is equal to the sum of the individual powers used by each circuit component: Ptotal = P1 + P2 + ... + Pn Using (1) above, I can connect two 1 Ohm resistors in a series to get a total resistance of 2 Ohms. Using (2) and (3), I know the total voltage drop across both resistors will equal 5.15 volts and since each resistor comprises half the total resistance, each will drop 2.575 volts. Using (4) and applying my power formula, each resistor will dissipate 6.63 watts of power, i.e. P1 = V2 / R1 = 2.5752 / 1 ~ 6.63 watts. Total power = 6.63 + 6.63 = 13.26 watts.

The Fix By using two easily obtained 1 Ohm 10 Watt resistors (Radio Shack), we can wire them in series across the +5 volt (red/black) output and increase the load on our power supply with an attendant increase in output voltage on the 12 volt line. Both resistors will be running at about 65% of their rated wattage and will not be damaged by overload. However, they will get very hot -- the single 10 Ohm resistor was dumping about 2.65 watts while each of the 1 Ohm resistors will generate nearly 2.5 times that. To keep them cooled down, it is strongly suggested that both be attached to the PS case with heatsink compound to help reduce heat buildup. On the power supplies I have tested, all produced higher voltage levels, with increases of .15 to .2 volts and total output of 11.85 to 12.06 volts. If you are converting your PC power supply with the intention of driving a field charger, you might consider the substitution indicated above to get a little more voltage. Be mindful that the conversion comes with a tradeoff in the form of more heat. However, a little care in heatsinking your resistors should provide a reliable and long lasting source for regulated DC power. Unexpected Shutdown -- I've made the recommended changes, but when I connect my charger, the PS still shuts down. Now what?? The usage of a PC powersupply as a substitute for a field charger power source falls far outside the intent of the original design specifications. Once the PS is running and stable, the overload circuitry is tuned to detect high current sinks and shut the PS down -- under normal usage, these sinks would be indicative of an internal short in the PC. When a microcomputer is running, powersupply demands change, but these are minimal and are usually associated with optical, hard or floppy drive usage or USB devices being attached. Some field chargers produce a high current sink when first attached and generate a latch into the overload state -- as designed. The specifications state that the PS will remain latched until the load is removed from the rail -- the PS will either automatically reset or may require at least one PS_ON cycle. Even though your PS may have sufficient wattage to effectively drive the charger, the load change is the problem. One method that has been effective is to attach the charger before powering up -- to the PS, the charger

now appears as a high draw motherboard and not as a potential short occurring after the PS is stable. Doesn't work!!! -- When I tested my PS before making the conversion, it worked fine, but now it won't power up at all. What should I try?? If the power supply were functioning before being modified, there are two prime suspects to check out. A failure to correctly reconnect the remote sense wires can keep some PS from latching on. See the Design Guide Update for remote sensing information. The other likely culprit is a short causing the overload circuitry to capture. Occasionally, this will cause a fan bump -- the fan will attempt to spin up, then stop and there will be no voltage on the output rails. Cycling the ON/OFF switch produces the same result: a bump, then Latch_Off. Check your internal wiring to ensure none of the clipped ends are shorted to the case or another rail. A second potential source for shorting is binding posts. The majority of binding posts have either a plastic bushing that passes thru the case or a shoulder on the post and retaining washer that keeps the post centered. Occasionally, the second style will not be correctly centered and the bare threaded post will come into contact with the PS case. With the PS unplugged and using your VOM or DMM, test each post in turn for a short to the case -- none of the DC rails, including GROUND, should have case contact. The case is grounded on the AC side; the DC side is isolated. If one appears grounded to the case, realign the post and test again. Should none of modifications prove workable, your only remaining solution may be to purchase a standard benchtop powersupply from a retail vendor or one of the on-line auction sites -- perhaps not as satisfying as a DIY project, but it will get you back into the air. BACK Updated: March 13, 2009

Power_OK or Power_Good Myth or Fact The primary purpose of the PC power supply is to supply stable current and voltage of differing levels to the motherboard and various peripherals attached to our PC's. The ATX design guides are very specific with respect to voltage levels, acceptable variation, overload circuitry, plug design and even screw-hole placement on the PS cases themselves. As many of you are aware, the personal computers today do not function well with fluctuating voltage levels and may be damaged if operated in a less than ideal electrical environment. One of the design specifications ensures that the system will not function if voltages are not sufficient to operate the system properly. In short, the PS is designed to complete a series of Power On Self Tests (POST) before the motherboard starts to powerup. These tests determine if all the voltages are up to design specification and stable before sending a signal to the motherboard. If the POST completes successfully, a POWER_GOOD or POWER_OK signal is sent to the processor over the POWER_GOOD line. This signal must be continuously present for the system to operate and, if withdrawn (due to a brownout, for instance), will generate a system RESET. The system will remain in a continuous RESET mode until the signal is restored. Since the processor initializes in the RESET mode, the system will not start until sensing the PWR_OK signal.

This signal is a +5V active (nominal) high, usually present within 100ms to 500ms after applying A/C to the powersupply. Active high means that as long as the PS is functioning properly (active), the signal can be measured. There may be some variation in the voltage level on this line, but ranges of +2.4V to +6.0V are generally considered to be sufficient to force the processor out of RESET. Since the signal is generated by the PS for use by the MPU, the PWR_OK (gray) wire should not be grounded, attached to any of the other output lines or tied to a resistor. It is not required for the PS to function -- its sole purpose is to allow the motherboard to initiate the boot process and to continue to function in the absence of unstable or improper power levels. Could this signal be of any use when converting a PC powersupply to desktop usage? Realistically, the answer is YES. A voltage on the PWR_OK line indicates that the PS has completed a successful POST and that the output voltages are stable and within design specification. If you wanted to use an LED (light emitting diode) as an indicator that the PS is on, rather than tie it to one of the +5V or +12V lines, attach the PWR_OK line to the anode (+) side of the LED and place a 220 ohm resistor on the cathode (-) leg before grounding it. The cathode leg is normally shorter on new LEDs -- if the legs have been clipped, the cathode will be on the same side as a flat spot on the LED base. The LED should be bright for normal operation -- it could possibly glow faintly if the PS has withdrawn the signal simply due to bleedover. After having read several news groups and had some inquiries relative to this function, I thought I would add this short section to clarify the purpose and operation of the PWR_OK signal. I hope it has been of use. BACK

Gray = PG o da = “Power Good” demekmiş. Ana karta bilgi veriyor olabilir mi?

24-pin ATX12V 2.x power supply connector (20-pin omits the last 4: 11, 12, 23 and 24)

Color

Orange

Signal

Pin Pin

+3.3 V 1

Signal

Color

+3.3V

Orange

+3.3 V sense

Brown

13

Orange

+3.3 V 2

14 −12 V

Blue

Black

Ground 3

15 Ground

Black

16 Power on

Green

Ground 5

17 Ground

Black

+5 V 6

18 Ground

Black

Black

Ground 7

19 Ground

Black

Grey

Power good 8

Red

Black

Red

+5 V 4

Purple +5 V standby 9

20 −5 V (optional) White

21 +5 V

Red

Yellow

+12 V 10 22 +5 V

Red

Yellow

+12 V 11 23 +5 V

Red

Orange

+3.3 V 12 24 Ground

Black