This is my first computer, and it was rested in 2006 after five years of use, with this exact complaint. It was taken to a service center and restored and returned with the remark that the processor failed and needed replacement, but I built a new Pentium D rig and stored this.
A few months ago I took it out, cleaned well with IPA and tried. It was booting as usual. I used it very sparingly and in some days it went between performing as usual, quick reboots and the problem mentioned above. I could install Windows XP and puppy linux, upgrade the BIOS, and have general use and even leave it on overnight. This led me to believe that the processor quit working due to overheating, because of which it had to be taken to the service center and was going to do okay if cooled properly.
As of now, the CPU fan works, the mobo LED lights up and the LEDs in the keyboard and mouse light up, but the other mobo based fans won't work and the front panel LEDs won't light up. The HDD shows activity if connected to the PSU.
I believe this is a very common problem as I find many threads about this, but with nearly no solution for many. I believe the answer is between a failed motherboard and a failed processor. Physically all components are intact. I tried typical things like building it from scratch, leaving the battery out and then putting it in, etc. No positive result. I am beginning to believe that most likely some MOSFET needs to be replaced.
Has anybody else encountered this kind of issue? What were the solutions tried and the ones that worked in these or similar cases?
I took the thing to the repairman, he put a replacement processor of 900MHz 100MHz FSB in there and said that he worked some bit in the CPU section, for about Rs. 500/- (~$9-10).
It works fine now with a newer PSU and not the old one. With the old one it requires CMOS clear up each time.
Although a newer PSU of nearly 250 Watts is cheap enough to buy, I'm trying to find a way to rectify the older PSU. I believe I will start another thread in the relevant section for that. For here, the details of the PSU are:
DEER PCB with DR-200ATX v2.02 printed on it. It was sold as the brand Zebronics here in India. Some browning of the board is there at one of the resistors R66. I replaced a pair of capacitors which I believed leaked electrolyte.