Possible motherboard problem


Jun 20, 2009
hi all,
got a friend with a problem displaying anything on his monitor. one day it was fine the next nothing.

he is running a 9600gt and i thought this may be the problem so i changed it out for a 8600gt that i knew worked and still no display, so i tried the onboard graphics with still no luck.

so from this i tried another monitor that i knew worked off my rig and still no display.

from this point i thought i would start from basics, stripp it all out and just run the psu, motherboard and cpu. when running it with the basics i still get no display so assumed that i would be the mobo or cpu.

everything powers up as normal and after leaving it running for a while the cpu heatsink gets warm and upto normal temp from what i can feel, do you think this points towards the motherboard.

on the hdd led, it gets two quick flashes but then nothing after this.

any help would be great. any other information needed just ask

Unfortunately, it could be almost anything including the power suppy.

When you are asking for help, always start off with the system specifications.

(My standard troubleshooting reply follows.)

However, onward to some systematic troubleshooting techniques.
If a new build, start here:

Work systematically 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.

If no luck, continue.

If a not new build (a formerly working computer), start here:
The following is an expansion of my troubleshooting tips in the breadboarding link in the "Cannot boot" thread.

I have tested the following beep patterns on Gigabyte, eVGA, and ECS motherboards. Other BIOS' may be different, but they all use a single short beep for a successful POST.

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 (standby power supply): 5 volts always on. The green wire should also have 5 volts on it. It should go to 0 volts when you press the case power button, then back to 5 volts when you release the case power switch. 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, long single beeps, or series of short beeps indicate a problem with the memory. If you get short beeps verify that the memory is in the appropriate motherboard slots.

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.



Jun 20, 2009
system specs as followed:

cpu- phenom 9550
mobo - am2+ biostar ( not sure of the serial as i am not with the system now but can get it if needed.
memory- samsung 2x2gb ddr 800
gpu- nvidia 9600gt
psu- 650w runnign dual rails 20a each total of 40a on +12v
lite on optical drive
wd 500gb hdd
some random case
22" monitor

One of the problem i came across was that their is no bleep sequence but then their never was any bleeps at any point, i will test with a new power supply that i know works.