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Dead Video Card or bad PSU?

Last response: in Graphics & Displays
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October 7, 2010 7:36:12 PM

So for the past month ive been having tons of trouble with my computer..... parts werent working so i troubleshooted like crazy...
eventually after a while i thought it was the motherboard and the ram. But in the end the computer wouldn't post.
I just got a new PSU since i had a previous SLi setup with 2 GTX 260s 216. But they were locking up constantly and one of the cards stoppped working. It would freeze up every time i put it on and ran any 3d application. Assuming it was power i got a new one. Now my other older card was working fine and out of the blue... it just would no longer post...i requested RMA's and before i sent them i tried the mobo outside the case 1 ram and CPU , no hDD, no Disk drive....and it worked...i connected the video card and nothing.. tried the card on another board same thing... no post or video..
is the card deaD?
or is the PSU faulty?


MB:MSI NF 750 G55
GPU:Built In.
RAM: 4GB ddr3 1333mhz RAM
HDD: 300GB hDD 7200 Rpm
CPU: Phenom 2 x4 955 @ 3.20GHz
PSU: Corsair tx850 Watt PSU
Disk Drives: One DVD burner
a b U Graphics card
October 7, 2010 8:06:46 PM

Work through our standard checklist and troubleshooting thread:
http://www.tomshardware.com/forum/261145-31-read-postin...
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 not, continue.

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

Breadboard - that will help isolate any kind of case problem you might have.
http://www.tomshardware.com/forum/262730-31-breadboardi...

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.

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.
http://www.youtube.com/watch?v=5FWXgQSokF4&feature=yout...

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.

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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October 7, 2010 8:26:39 PM

The system boots up fine...WITH OUT the video card installed...
when i INSTALL the video card it just powers up but theirs no video nor is their any POST beep, or ANY beep at all... my old PSU wasnt working correcty so i dont want to try anything with that one..
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a c 160 U Graphics card
October 7, 2010 9:40:27 PM

You moved the card and it also failed, I'd say it's the card, OR maybe.. the PCIe slot.

Have you tried another card with the mobo?
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October 7, 2010 11:23:22 PM

Yep...
i tried my other card before sending it out and it posted...
the one im returning locks up all the time...since i bought it.
The other one just doesnt POST...

new video card for me then.

THanks for the help.
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