I checked the temperature of the cpu using a temp. software... it displayed 80c... but when I push the cpu fan against the cpu, the temp. reduces, if I let go, it increases... I checked and found two side holders of the cpu fan are broken.

I held it for about 3 minutes and the temp. dropped at 49c. after that... the system is working gud till then. but if I run some program and game, the temp. increases to 56c to 63c... if it reaches 85, the system hangs up and shuts down.

I think I should get a new fan.
what do you recommend...?

Thermaltake.
Costs more then most.

depends on what type of socket you have. not all heatsinks are created equal. some are great for extreme cooling but costs lots, and others do the trick and are releatively cheap. which route would you like to go? Also what socket is your computer? (if you dont know you can just say the motherboard model and i can find out)

Don't forget to check the dimensions available for the new fan. Those heatsinks can be too big to fit in.
What I did is went to a pc shop with a lot of fans and cool(ing) stuff on display and told salesman what CPU I have. (thermaltake clone costed me ~$30..... golden orb II or something, a good choice)

My motherboard is Intel D845WN, the worst one I ever saw. It says in its manual that, this m/b has been designed for 1.3-1.8 ghz processor... but I replaced it with a 2.0 ghz... which is not supported, I think that's where the whole problem begun.

If it says that 1.8 GHz is the best it can support, that dosn't mean 2.0 won't work. It can be that 1.8 was the best available CPU for that slot. If your system says (my computer/properties) that CPU is 2.0 then it's working. Run DXDiag.exe to be sure (first page gives you current CPU frequency).

I appreciate your help, thanks alot. now let's get back to business...
How do I know if a RAM is corrupted...

I already have a 256 MB(PC133) placed on the m/b... I have another 128 MB(PC133), but don't know if its gud or corrupt...

I placed it on and the system properties show me 384 MB... is there any specific way to find that out?

Try http://www.memtest86.com/mem32.zip if you have floppy drive or http://www.memtest86.com/memtest86-3.2.iso.zip if you have cdr.

It's free and trust-worthy.