PC Restarts/crash - Weird problem - Please try to help

[craige_4u]

Okay for the past certain days my PC crashes, here are the things i done:

- Formatted Completely
- All drivers Tested (No driver Problem)
- NO hardware/software changes done
- RAM is all okay tested by software and used new memory also
- All connections are okay
- There is no heating
- Defragmented
- Used New another HD (tht too carshed)

My PC doesn't start at one go... i mean it starts and boots with the desktop and it works for around 30secs-1min, and then it crashes and restarts.
Sumtimes, it also keeps on restarting by itself without getting booted properly.

The PC then after 5-6 crashes starts properly and works like nothing have happened, all works great afterwards.

So, the probs is the PC doesnt start at one go without crashing 5-6 times in a row.
Rarely, it crashes while working(No particular Software- Randomly)

What it can be?
Power supply ? But then how come when it works it works properly for hours.

Just try to help out - any software to check power supply?
Any software to check problems with graphic card ?
Provide an link please.

Also, there are No Error messages and i also disabled automatic restart when PC fails to respond function.

[Cricket]

What kind of computer is this? Home built or name brand?

What are the complete system specs? List all parts by make and model including the power supply.

Cricket

[flanzig1]

Could still be a PSU problem even if if the computer runs OK after a succesful boot. A computer start up is when the PSU is under the most strain. If a cheap or old or undersized PSU, some of the components may not be able to handle the initial in-rush of current.