computer wont turn on, no beeps, no picture

[joethomas3000]

I decided to rebuild my computer, its  an asus with a nvidia graphics card thing in and 512mb of ram, ive tried clearing CMOS and nothing :S everything is wired correctly so i think it is something to do with the graphics card

[quaxo]

Graphics cards will generate a beep.

Look into the processor, power supply, or possibly the memory.

[joethomas3000]

ive tried 2 power supplies and 2 hard drives and the processor has no missing pins and should be in fine

[Transfusion]

Is the fan spinning? When you turn on the PC do the fans start and then stop abruptly?
Take out the graphics card and try the onboard gfx, it might be the power supply not providing enough power...

[quaxo]

ive tried 2 power supplies and 2 hard drives and the processor has no missing pins and should be in fine

Hard drives wouldn't cause this issue anyway. They would generate an error at POST or boot. Try with just one stick of memory (if you've got more than one in). Possible the motherboard or processor still, or as Transfusion mentioned, underpowered power supplies.

Can you give a thorough list of the hardware in your computer?

[joethomas3000]

Motherboard: Asus A7N8X-8
Power Supply: Winpower ATX-450
Processor: AMD ATHLON

I dont see why it should be underpowered it is the same power supply i had before and it was working perfectly fine.

@Transfusion The fans are fine ive had it running for an hour just to check for any overheating etc and its all fine the fans are working however with my motherboard there is no onboard gfx

[Transfusion]

This is one old motherboard. 2003???
Im afraid you will have to give us details on the upgrades you performed... All I can think of is
1) incompatible processor
2) Ram not seated properly
3) atx 12V (the one with 4 pins) not connected properly.

[jason2074]

I decided to rebuild my computer

Check your Video card and RAM module for any oxidation buildup on contacts. If necessary, reseat them properly or remove all RAM to check on no post/beep. The other probable way of checking this is to use another RAM and Video card to test. Unless there is something wrong with the mobo, since you mentioned having to rebuild this without knowing how it was working previously and how it was kept properly overtime.

[joethomas3000]

Check your Video card and RAM module for any oxidation buildup on contacts. If necessary, reseat them properly or remove all RAM to check on no post/beep. The other probable way of checking this is to use another RAM and Video card to test. Unless there is something wrong with the mobo, since you mentioned having to rebuild this without knowing how it was working previously and how it was kept properly overtime.

Generally no idea what your on about in most things there haha

This is one old motherboard. 2003???
Im afraid you will have to give us details on the upgrades you performed... All I can think of is
1) incompatible processor
2) Ram not seated properly
3) atx 12V (the one with 4 pins) not connected properly.

what do you mean by #3 and it couldnt be the processor because i used it for years before i decided to rebuild it and i have already tried reseating the ram, i didnt change and components i just rebuilt it out of boardem

(thanks to all the people who have joined in the discussion so far 

[Transfusion]

A faulty 12V motherboard connector could be the culprit.

[joethomas3000]

A faulty 12V motherboard connector could be the culprit.

How would i check if it was faulty

[Transfusion]

http://www.hardwareheaven.com/guides/testingPSU/

[joethomas3000]

thanks for that ill check it out a.s.a.p.

[Computer_Commando]

I decided to rebuild my computer, its  an asus with a nvidia graphics card thing in and 512mb of ram, ive tried clearing CMOS and nothing :S everything is wired correctly so i think it is something to do with the graphics card

Please define what you mean by "rebuild my computer".

[joethomas3000]

just take everything apart and put it back together