My pc reboot many times

[shacalilung]

my pc reboot many times...
when i open the computer..and will start and thats all and it will restart and restart all over again..
and its newly reformat about 3 days now...
plsss help me what's wrong with my pc....
thanks..and god speed....

my pc its old enough...
processor: intel pentium III 700 MHz
L2 cuche:256 kb
Memory 256 MB
Mainboard Trigem computer INC Nara-A
Monitor plug and play
Videocard 3Dfx interactive inc banshee
mode 800x600 with 32 bit color deph

and its just randomly reboot itself without and message....

 

[Tedster]

1. have you tested your ram?
2. have you checked your registry?
3. have you tested your PSU?

What diagnostics have you performed?

 

[shacalilung]

my pc was newly formatted..how can i check the RAM,registry even the PSU if the computer its rebooting randomly and i cant even performed a single task on it..
its like this when i open the pc and its just rebboot and reboot and reboot what i will do is just unplug it coz even turn off i cant do it...
thanks for your reply...pls help me with this...