My 486 pc freezes especially when playing games and loading graphics. For example if in wolfenstein3d it freezes when loading a new picture and also it freezed when I scroll through the menu to fast with the keyboard.

I already testet the memory with memtrsr and it have no problems.
I also used scandisk to test the hdd also no problems there.
And also no cpu errors with checkit.

Also I realized when I turn off the internal cache the freezes occur more rare than with internal cache on. However underklocking the cpu with 35mhz instead of 50mhz make freezing worse.

What I also realize: when I turn the color depth higher in win95 the lcd monitor i use have some strange noise. But this could be also because a analog signal goes to a digital lcd monitor.

So my guess is: broken onboard graphics/vram, power suply, broken cpu, broken motherboard

What do you think is the problem here?

I have no other AT power suply, no isa vga graphics card or other 486 cpu at home to test and i dont want to buy all 3 things bc they are all very expensive. So I want to find out the problem to only buy oke of those to fix the problem.