System shutsdown abruptly

Hi,

I have a pc with below configuration. Been using this for the past 2 years.
Asus Mobo A7n-266VM
AMD Athlon 64 X2 Dual Core 4800+
Transcend RAM 2 GB

My PC shuts down suddenly after roughly 15-20 mins of booting.Bothe the CPU and power supply fans are working fine.

I tried watching the CPU temperature in the BIOS. It starts at around 41C and goes till 55C when the monitor goes to stand by but the CPU is still ON/running.

Now i am clueless.. no second rig to test by swapping each part.... Help .... pls

 

you need to be more specific.
when you say booting do you mean while you are in windows already and using it or just constantly rebooting it?
does it completely power off and turning it on yields the cpu fans and psu fans working but no video?
explain in detail exactly what it does step by step. those temps are normal.
you could check to see if your video card is overheating.
at the point where it shuts off, feel the heatsink on the cpu fan to see if its hot to the touch.
feel the power supply to see if that gets hot.
are your shutdowns random or do you really have 15-20 mins from when the pc was off for a long time? (this could be related to heat)
if it only starts working after the pc has been off for a while, check for things that may be overheating.
try resetting your bios settings to safe or optimal settings and see if its persists.
turn off any suspend/sleep features in your bios. turn off acpi.
also feel any chipsets on your motherboard to see if those are hot to the touch upon it shutting down.

 

Usually means heat problem, What does it do when it is in safe mode ??? will it shut off then ?

 

I'm under the impression the machine will always shut down and completely power off when too hot, safe mode or not as it's managed outside of the OS as a built in function to prevent damage. As violet says, is it completely shutting off, or do fans continue to run? It does sound like an overheating issue despite the temps you posted being normal. If it is completely shutting off you might want to take a look at the PSU make sure it's not hot to touch, also is it from a reliable brand rather than a 'bundled' one that comes free with a case - they can often be unreliable.