Diagnosing non-POST-ing computer

[Nautalisk]

Hey, I have been trying to fix my friends Dell Inspirion 531s for about a week now, and was hoping I could find some help.
One day his computer just decided to no longer boot (he had been getting some BSOD's about his HDD) and instead, all the case fans turn on, CPU fan, and Graphics card, but the screen remains blank, all it is getting is a blank signal and then goes into sleep mode.

There is no POST... or even an internal speaker as far as I could find... so after some searching on forums I decided to replace his Mobo. We did that, but we still get no POST and the same issue (recently though, I found on these forums that I should also make sure that my standoffs are not shorting out the Mobo, and I am going to test his RAM, by putting in 1 of my working sticks (I will be doing this tomarrow)).

I think that it is his CPU that is actually bad b/c if I am not mistaken, they must generate the POST and if is is dead then, you wouldn't get one(he now has an internal speaker due to a case switch) So, besides putting the CPU in another computer is there any other way to diagnose this, or any other possibilities it could be?

His specs are: (sorry not the best, don't have his comp w/ me at the moment)
CPU: AMD Athlon X2 4450E
(New) Mobo: ASRock ALiveNF5SLI-1394
RAM: 2.0 GB DDR2 SDRAM
(Temporary) Graphics Card: Nvidia 8800 GTS 512MB

 

[Guest]

Stand-offs shouldn't short out mobo if you have only used them where there are screw holes in the board. From your description, all that's left to test is the memory or the CPU.

I would install a speaker -- any 8ohm unit can be used and you just need to connect it to the correct pins using a spare connector (if necessary taken from an LED).

If possible install an alternative, simple, graphics card -- these clever ones can cause problems. If you haven't been able to see anything at all on screen apart from a message generated by the monitor itself, have you tried swapping monitors .

 

[Nautalisk]

1. on the stand-off's, Thanks for the info I will keep that in mind
2. Sorry I put is kind of weird in my message, but we do have an internal speaker now, and its still not getting any form of a POST when we boot up
3. Technically he has had 2 graphics cards to test with, since his old Mobo was using integrated graphics and my 8800 GTS (letting him barrow for testing while we pick out a new one for him) and they both yielded the same results
4. on the monitor... idk why I haven't tried that... heh, I'll do that today, just in case....