Help my PC turns on and off then back on!

[Simpleton]

I turn it on and all fans spin but, it turns off after 3 sec then back on after 5 sec and stays on with no video signal.

I recently purchased a new PSU and GPU, the problem was happening before I bought the new stuff.

Here are my current specs

CPU - intel dual core E5700 775 (I think)
GPU - Nvidia GeForce 8800 GTX 768MB
PSU - Arctic Power 500w
MOBO - P5G41T-M LX2/GB
RAM - Rendition 2GB DDR3 240 PC3

All of the above is brand new apart from the PSU and GPU.

Thanks for reading, I hope you guys can help me out

 

[Arris]

Have to go back to basics.
Check everything is correctly and fully seated in slots/sockets.
The Geforce 8800 GTX requires additional PCI-E power connections, have you definitely connected power to the additional connection?
Does the machine beep or show anything on screen at all briefly before it restarts?

 

[Simpleton]

Hi thanks for reply.

I have checked that everything is seated correctly, I have two pcie power cables plugged in. Nothing on screen an no beeps just a blue no signal screen

 

[Arris]

Can you hear hard disk activity to tell if the machine is actually continuing and booting the OS?
Or is it deathly silent? I had a 8800 GTX that died on me after some weird artifacts appeared for a while and that's pretty much the result. Do you know anyone who could let you try their video card in the machine or your card in theirs just to try and figure out what is preventing the system from working?

 

[Simpleton]

Yeah the HDD boots at start, I'm goin to my friends on Monday to test all my stuff but it's been two week sinse the problem started. I feel like smashing it up!!! I have lost hair you know

 

[Arris]

Yeah, I think we've all been there at one time or other. Hope the news from your testing on Monday is good and no expensive parts are needed to fix it

 

[Simpleton]

Well I hope so if ulook up my specs you won't find a part over 50 quid but saying that if it's a couple of broken parts am still looking to pay out £100 yikes. I will post back then to let you know. Thanks mate

 

[Arris]

Any update? Did using your friends computer as a test bed let you find out what the problem was?