PC Keeps restarting, without getting into BIOS

Hi all!

I have a problem.. Suddenly, my PC didn't start up anymore. Didn't even get into BIOS (Screen keeps showing "No signal", and than the pc just restarts automatically. Didn't change BIOS (yeah, about two weeks ago I did).

So, I opened my case, thought it might be a power flaw, and therefore I disconnected one of three hard drives. It started up...

I, happy ofcourse, then connected a new hard drive i still had to connect. Again, it did start up, untill vista checks the hard drive, somehow i hear that windows starts up, but the DOS-like screen with the information about the hard drive stays on screen... strange, so i restarted.

Without succes again...

So foar for the history, the problem now persists.

Exchanged memory, used all slots and different memory.
Disconnected everything, all hard drives, disc drive: keeps restarting.
When i disconnected the graphics card: it doesn't seem to restart.
Connected the hard drives again: still does'n't seem to restart.
Connected the graphics card again: restarts again, on and on.....

So my question is: is it most likely to be a graphics card defect, or is the power supply the problem? Or might it be another problem?

I use a MSI p45 neo4-fr, OCZ 550 Watt power supply, and a Ati radeon 3870 from Sapphire.

I hope someone can help me!

first try default setting in bios. perchaps by chance some settings were changed and now cause instability. check especially memory voltages in your BIOS. if everything will be okay, we can start thinking about other possilibities.

Out of curiosity, when you removed everything you are not including your CPU fan and heat sink are you? Cause the fan not being connected or connected improperly could be doing that too you.

You have just 2 suspect components, PSU and Graphics card.

I had encountered the same problem once. It was the RAM. Check and see if the RAM is supported by your Mobo. It may say it is supported but that requires you to update your BIOS. Try to get some RAMs that are already out in the market for sometime to ensure that your Mobo supports it. Out of curiosity, what Mobo & RAMs are you using right now? Would be helpful if you list the parts name and model.

I would also like to add that if Memory is not correctly detected, no data can be allocated a memory resource, hence the restarts occur. However, this is only a guess to your case as yours may differ from mine.

"New build won't boot" checklist

http://www.tomshardware.com/forum/ [...] -checklist

Hmm okay, have tried it for a few seconds already, but will give it a go tonight... when it still doesn't work, i will try all the components in an other (similar) pc this saturday. Hopefully i can then rule out some components.

I believe there are no LEDs on the mobo, but will check that also.

Thanks so far...