Desktop Building Troubles

Hey all,

I'm going to tell you the full story of my situation, as you might see something small in it that is mucking everything up.

I'm building a desktop computer for myself, and recently bought all the parts needed to get it going, including an Intel Core 2 Duo e7500 cpu, a Gigabyte P35C-DS3R Motherboard, and a GeForce 8800 GTS 512mb ddr3 graphics card. I went and turned it on, installed windows, then turned it off again because I didn't have the time for anything else for the moment.

The next day I got home, turned it on and the graphics card starts making this loud beeping sound. Turned it off wondering what the problem is, to find my brother had taken out the PCIE 6 pin convertor cable for the graphics card out, so I get it off him and put it back in. This is the only thing that either of us are aware was touched on the computer between the first startup and the second. On the second attempted startup, the graphics card isn't making that sound anymore (so I assume the PCIE 6-pin cable missing was the problem), but the fan goes on high, and the monitor light goes green, then says 'monitor going to sleep' and the light goes orange (monitor goes into standby). About 10 seconds after that, the PC powers down for a few seconds, then starts up again, with the same result (and does this again and again).

Now, take note the motherboard I bought was second hand, and the guy said he slightly damaged it, but it was still working for him when he sold it (dont tell me its a bad idea to buy second hand, I know that now haha). So thinking that was the problem, I buy a brand new motherboard - ASRock G31M-S R2.0 (whatever R2.0 means). I also took the graphics card out to eliminate variables, as the ASRock MB has integrated graphics.

Same thing happens, exept it doesn't restart with this motherboard, it stays on (I'm thinking its just the way the other one was made, to restart the system if something goes wrong).

So then I get the idea that since two motherboards are doing the same thing, it could be the CPU that is in fact faulty. So I get a friend to come around and I put his CPU (Intel Core 2 Duo e6550) into the computer. Same thing happens.

From then I put his 400W power supply into the computer (mine is 420W, but relatively older) - same thing happens. Once he puts his back together again, I plug his computer into the monitor just to make sure it isn't actually the monitor that isn't working, and the monitor doesn't have a problem.

So now I've pretty much established that the motherboard isn't the problem, the CPU isn't the problem, the power supply isn't the problem, the graphics card isn't the problem (using integrated for the moment), and I've unplugged pretty much everything else to eliminate variables... so by rights IT SHOULD be working, but its not. I just can't figure out what to try next. Everything is compatible (as far as I know).

Could I have luck bad enough that two of the components are faulty?

Any suggestions on what to try next would be EXTREMELY appreciated, as I've been struggling with this for 3 weeks now.

 

Never, ever use 6pin pci-e converters! (pressuming you used the 4 pin molex to 6 pin pci-e cable?)

They do not supply sufficient power to the GPU.

This is a nasty troubleshooting problem.

Did you use the same cable when you used your friends PSU?

My guess is that the PSU and GPU are dead. But a guess is exactly what it is.

Keep trying my friend, you will get to the bottom of this!

I know how frustrating these things can be!

 

Thanks for the suggestion Burrell, I might go back to the friends computer, and instead of taking his part out and putting it in my pc, taking my part out and putting them in his, testing one at a time. Cables are a good point... though the only cables I used really are the power supply-motherboard and power supply-CPU, and I swapped both of those when I used his power supply.

Just a question - could the CPU fan have anything to do with it? Is it essential that it works flawlessly for the computer to power up and work? (obviously not for more than a short amount of time)

And another question - why shouldn't I use a 6-pin convertor cable? What else should I use? Just to clear anything up, this is what I consider a 6-pin convertor cable:
http://www.tomtop.com/images/l/200911/12589659110.jpg

Thanks for the response anyhow.