computer restart after windows logo

Hi would someone please help me with my problem?

I got a windows xp SP2 installed in my desktop.
The problem is, when i start my PC, it loads until when it comes to windows logo, it restarts again just like that in a loop.

I have tried safe mode but did the same.

Also when i run chkdsk /r it didn’t fixed it.

I also repair windows xp (inplace upgrade) and when it reboots in the process the computer restarts and so the repair cannot be completed.

Please can someone assist..