Problem with custom built computer

Hi, I'm having a problem with a computer I have obtained, I've traced the problem down as close as the motherboard or the PSU, the case is the Silentium T1 Pro;

It came with a AX500-F PSU built in. The graphics card requires both the PCI-e connectors to be connected. At first, the screen would go blank after some time with the computer working fine, and it would be difficult to restart the computer. I managed to get it to play an itunes track, and after the screen going blank iTunes would carry on playing. It then went through a phase where it would get half way through boot (normal or safe mode), and then just cut out to the initial bios splash screen and start again. If it was in safe mode, it would get as far as iomdisk.sys in the list of startup files before rebooting.

Now, it will cut the power after 4 seconds, before anything has shown on the screen.

I have access to all sorts of various parts but cannot find any suitable replacement motherboard or psu or graphics card so I can swap them out for testing purposes, so before I go ahead and pick one of the 3 at random to buy and test, I'm wondering if anyone here can shed any light.

I've tried taking the RAM out (2x1GB), 1 at a time, in the different sockets, removing the graphics card, disconnecting all the drives.

Very occasionally it will boot up and display the post screen and allow me into the bios (I've cleared the cmos using the jumper setting a few times too), and may boot as far as half way, but still fails.

The spec as I understand it is as follows:
Asus M2N32-SLI Premium Vista Edition motherboard
Athlon XP processor of some sort (really not sure which)
Sapphire HD2900XT graphics PCI-e (appears to need both PCI-e power cables from PSU)
Arctic Cooling Silentium T1 Pro case...
...with built in AC AX-500F PSU (not standard ATX form factor)

I'm at a bit of a loss also because of the non-standard PSU
2 answers Last reply
More about problem custom built computer
  1. Hello and welcome to the forums
    Is it possible for you to test your PSU in another system ? or test another PSU in your case ?
  2. Work through our standard checklist and troubleshooting thread:
    I mean work through, not just read over it.

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

    Breadboard with just motherboard, CPU & HSF, case speaker, and PSU. You do have a case speaker installed, right? If not, you really, really need one. If your case or motherboard didn't come with a system speaker, you can buy one here:

    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:
    At this point, you can sort of check the PSU. Try to borrow a known good PSU. 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.

    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.

    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.
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