Well I've managed to find some free time to tinker deeply with the system. Using the DEBUG DOS program for configuring the southbridge and the WPCREDIT program for northbridge (via PCI host adapter) I was able to test different combinations of both 8/16 bit I/O recovery times and 8/16 bit DMA wait states. I haven't tried all possible combinations, only 2-3 of them (like 4 CLK I/O wait states), but that didn't improve the situation. The only small difference that I've observed is that when I set some DMA wait state the computer just hanged in that case with the windows on screens... in all other situations and cases the system has been rebooting automatically. I've also tried to completely disable COM1 port but this time I've had the same problem with keyboard interaction during music playback. Either way I'm out of options for now and will keep PCI sound card until something else comes to my mind.
Finally the 10ns cache chips (for 512k cache) arrived! I've had only a half an hour this morning to try and play with them in the system. Definitely a progress compared to the old 15ns ones. QUAKE has been used for testing since it is the most demanding and heavily app for cache and memory. So far I'm not able to stabilize it in WB mode operation with 2x32MB EDO RAM, whereas with the 15ns chips (256k cache) it was fully stable. Anyway in WT mode (but again with 2x32MB RAM) everything seems good so far with only one exception - I've had to set DRAM write CAS pulse to 2 CLK, which was 1 CLK before. Otherwise the Quake hangs in the console graphic window in the beginning of demo. With 2 CLK several loops of Quake demo have been completed successfully. And what is more interesting, the results are faster than before with a tiny bit.
256k cache (2x32MB RAM) 10ns TAG, 15ns 4x 64kx8 chips:
18.8 fps full screen (health bar + ammo bar visible)
17.6 fps full screen (health bar only visible)
16.6 fps full screen (only 3D area)
512k cache (2x32MB RAM) 10ns TAG, 10ns 4x 128kx8 chips:
18.9 fps full screen (health bar + ammo bar visible)
17.7 fps full screen (health bar only visible)
16.7 fps full screen (only 3D area)
BIOS Timings (from the screenshot of BIOS Chipset options):
2-2-3 3-0-2-1-1 Slower
2 above is 2CLK DRAM write CAS pulse instead of 1CLK as before.
I'm looking to find out why I can't run the system in WB mode. It just hangs on "Locking 61Mb of memory..." when starting Quake demo. Right now in WT mode only half of the cache is actually used I guess (direct 1-way interleaving) and maybe that could be the reason the system is working fine. In WB it should use all 64MB of memory. So maybe there is some defective chip or a chip not working well at 10ns speed. I've bought a set of 10 pcs so I can try to swap them. Or I can also try to add another 64MB of memory (I've total of 4 32MB equal sticks) and try again in WT mode for full coverage. As I mentioned I didn't have enough time this morning to play around with more combos.
Do you know for a good model of working SRAM tester?