New power supply in gateway

I inherited a non working Gateway Select K7 950 along with a half bushel of dust, ****leburrs, and and assorted particles of other stuff accumulated in the P.S. and CPU fans. Blew it all out and finally determined the power supply had given up the ghost. I determined, with some help from this board that a generic power supply would work, and ordered a 300W power supply to replace the 200W. that was kaput.
To make a long story shorter I formatted the hard drive, installed my windows `98 upgrade over the Win 95 B, and it works just fine BUT, eight times out of ten when booting up it will drop out, reboot and open in safe mode, once I shut down and restart it, it usually boots up OK and works just fine. I checked and cleaned the ram stick, changed keyboard, took the CPU fan out and cleaned the blades, and still get the same results. I`m thinking about salvaging everything except the MOBO and upgrading this computer I`m using now. That`ll be another thread.
Any suggestions as to what to try?
I got the Recovery disk(s) with the computer but they set it up for ME and I don`t want ME. They are nice for drivers tho, got me sound and video!

 

I have found a sort of a pattern that may tell some knowlegable person something in the way of a clue.

I format the hard drive, install windows 95B and run the computer that way for a while. No sound card, no modem, only a video card, a PS2 mouse and keyboard. 75% of the time it will boot up and run OK, the other 25% of the time it will boot up to the point where the desktop would come up next, only instead, it will shut down and reboot and give me the options of safemode, normal, start, etc. I`ll open in safe mode, shutdown and usually things will work OK, Freecell,hearts ,etc, just to see if it gets hot and quits. That doesn`t seem to be the problem because even after sitting overnight, the first boot next morning may cause it to go into it`s routine.
If I install Windows `98 upgrade, it gets worse. probably shuts itself off about 60% of the time.
If I format and run all the gateway recovery disks and install ME, forget it! It boots up and works so seldom it just seems like a miracle when it does.
Any suggestions?
I`ve got a lot of patience, you gotta have when you don`t know what you`re doing