I got my hands on a Soyo SY-6KD Dual Slot 1 board (https://theretroweb.com/motherboards/s/soyo-sy-6kd) together with two P2-233 CPUs - and I am having some trouble getting this thing to run stably.
At the moment, the system has 256MB of PC-133 SDRAM, a Voodoo3 AGP, a SB AWE32 and a cheap realtek network card. At first it seemed to run stably but soon it started to behave weirdly: it crashes randomly - but only in single-processor OSs like DOS or Win98. If I use Win2000 or an SMP Linux system, it runs without issues (so far).
I use Quake/Quake 2 as a stability benchmark and let them run in their demo loop. Under DOS, Quake 1 crashes after ~1min. Under Win98, it runs a bit longer as does Q2, but sooner or later, it freezes too.
Windows 2000: No issues at all, Q1 and Q2 can run for hours
Linux (2.4 kernel with SMP support): Same as above, stable
Linux (same 2.4 kernel, but no SMP): Freezes in Q2 demo loop after a few minutes.
I also noticed that the system freezes under Win98 when playing some video file off CDROM (fine if played from HDD). Also, DMA cannot be enabled for CDROM under Win98, again, no problem under Linux or Win2k.
I already tried different RAM sticks, different graphics cards (AGP and PCI), no change. I checked the caps around the CPUs out of circuit, they are still fine.
Any thoughts? Do (early) SMP systems not work properly with single-core OSs?