Sign in with
Sign up | Sign in
Your question

No Post/CPU Fan on D975XBX2 System

Last response: in Systems
December 8, 2010 2:53:49 AM

Hi Folks,

My homebuilt system has suddenly stopped booting--I unplugged and then opened the case to look at the space around my PCI slot (getting a new graphics card) and I left the comp on it's side for the weekend. When I got back and plugged it back in again, no POST, no video, CPU and case fans won't turn on (but they do spin for a second when I turn OFF the PSU from the backswitch). The green LED power light on the mobo DOES turn on.

I have already tried most of what is in the PERFOMR THESE STEPS before posting sticky, except 1) Testing PSU with (don't have a multimeter) or breadboarding. Maybe someone here will have a bright idea to help me.

System Specs are:
d975xbx2 mobo
E4600 Core 2 Duo proc
2 x 2 GB Sticks DDR2 533 DIMMS
EVGA GTS 9600 GTX Video Card
2 SATA drives
2 Optical Drives IDE

So far I've done the following:

*Tried a different outlet
* reseated the memory, video card
* tried using each stick singly
* reseated the CPU and 20+4 power cables
* reseated the IDE cable and the SATA cables to all four drives
* checked that the front panel plugs to make sure they are all still firmly seated

Any suggestions? :) 

Best solution

a c 122 B Homebuilt system
December 9, 2010 6:56:12 AM

Beep pattern?

Work through our standard checklist and troubleshooting thread:
I mean work through, not just read over it. We spent a lot of time on this. It should find most of the problems.
I know you said you did most of it. What didn't you do?

If not, continue.

I have tested the following beep patterns on Gigabyte, eVGA, and ECS motherboards. Other BIOS' may be different.

Time to breadboard.

Breadboard - that will help isolate any kind of case problem you might have.

Breadboard with just motherboard, CPU & HSF, case speaker, and PSU.

Make sure you plug the CPU power cable in. The system will not boot without it.

I always breadboard a new build. It takes only a few minutes, and you know you are putting good parts in the case once you are finished.

You can turn on the PC by momentarily shorting the two pins that the case power switch goes to. You should hear a series of long, single beeps indicating memory problems. Silence indicates a problem with (in most likely order) the PSU, motherboard, or CPU. Remember, at this time, you do not have a graphics card installed so the load on your PSU will be reduced.

If no beeps:
Running fans and drives and motherboard LED's do not necessarily indicate a good PSU. In the absence of a single short beep, they also do not indicate that the system is booting.

At this point, you can sort of check the PSU. Try to borrow a known good PSU of around 550 - 600 watts. That will power just about any system with a single GPU. If you cannot do that, use a DMM to measure the voltages. Measure between the colored wires and either chassis ground or the black wires. Yellow wires should be 12 volts. Red wires: +5 volts, orange wires: +3.3 volts, blue wire : -12 volts, violet wire: 5 volts always on. Tolerances are +/- 5% except for the -12 volts which is +/- 10%.

The gray wire is really important. It should go from 0 to +5 volts when you turn the PSU on with the case switch. CPU needs this signal to boot.

You can turn on the PSU by completely disconnecting the PSU and using a paperclip or jumper wire to short the green wire to one of the neighboring black wires.

A way that might be easier is to use the main power plug. Working from the back of the plug where the wires come out, use a bare paperclip to short between the green wire and one of the neighboring black wires. That will do the same thing with an installed PSU. It is also an easy way to bypass a questionable case power switch.

This checks the PSU under no load conditions, so it is not completely reliable. But if it can not pass this, it is dead. Then repeat the checks with the PSU plugged into the computer to put a load on the PSU.

If the system beeps:
If it looks like the PSU is good, install a memory stick. Boot. Beep pattern should change to one long and several short beeps indicating a missing graphics card.

Silence or long single beeps indicate a problem with the memory.

Insert the video card and connect any necessary PCIe power connectors. Boot. At this point, the system should POST successfully (a single short beep). Notice that you do not need keyboard, mouse, monitor, or drives to successfully POST.
At this point, if the system doesn't work, it's either the video card or an inadequate PSU. Or rarely - the motherboard's PCIe interface.

Now start connecting the rest of the devices starting with the monitor, then keyboard and mouse, then the rest of the devices, testing after each step. It's possible that you can pass the POST with a defective video card. The POST routines can only check the video interface. It cannot check the internal parts of the video card.
Related resources
December 9, 2010 9:39:55 PM

arges86: Thanks for responding. No, this PSU was one I bought separately. Turns out both the PSU and the mobo went bad.

jsc: thanks for posting also There's no beep pattern. The PSU was dead, so I breadboarded and used a known good PSU: no beeps, nothing (used a screwdriver to try and short the power pins). I'm going to have to get a new mobo.
December 10, 2010 1:00:29 AM

thats rough
i'f i'd have to guess, the PSU prob. killed itself and the mobo at the same time

I really doubt both just died simultaneously
December 10, 2010 10:57:12 AM

It stinks because I can't afford to buy a new mobo, memory and processor right now, so I have to just replace the mobo with another socket 775 one. Spending money on keeping the same 3-year old build hurts my heart.
December 18, 2010 12:40:44 AM

I bought a replacement mobo: D975XBX2 (D53347-407).

* Started by breadboarding. With just CPU and HSF, no beeps, but when I shorted the power jumpers the CPU fan turned on. Just for giggles I tried adding memory, one stick at a time--no beeps or anything.

*Tried a different CPU: both an E4500 and Pent D930 produced no beeps on the board w/ no memory. I verified both CPUs in a separate build, and both booted up fine.

*Tried assembling the system just to see what would happen. Board power LED on, CPU fan/case fans turn on, video card fan on, but no video/post (monitor "sees" the card. i.e. no "no signal" message, just a black screen). I swapped out the PSU, memory, video card, two different processors, and all work fine in the other system (a D975XBX box).

* Went through the entire ""System won't boot" and "no video output" checklist," with no joy.

* I also went to this page ( and verified that both processors are supported by this board revision (no idea what BIOS, since I can't get any POST).

Would it be safe to conclude that the mobo is bad and RMA it?
December 25, 2010 4:07:27 AM

Best answer selected by Mandos.