I've been messing around with my newly restored Supermicro P54VL-PCI board:
The board is using the Opti "Premium" aka Opti Cobra chipset. Seems like it's an earlier Opti Pentium/VLB chipset with Opti Python being released a year later. I'm yet to see any info on which one of them is faster, but it does seem like Python allows setting different VLB speeds while Cobra limits VLB to 33 MHz.
This board supports up to 512KB L2 cache and takes Pentium 90 and Pentium 100. My current setup is:
Pentium 100
64MB EDO RAM
512KB cache
Tekram DC-680C cached IDE controller with 4MB cache and a 2.5GB Fujitsu HDD
Ark Logic ARK1000VL VLB video card with 2MB RAM
Voodoo 1 from Diamond
Turtle Beach Tropez Plus
Windows 95 RTM
The only thorough review of a Pentium VLB system I've found so far seems to be from WaybackTech (link).
A few differences:
- his board uses Python chipset, but he does not mention any settings for VLB
- his board allows tweaking cache/RAM timings, while my board wouldn't boot into Windows if I did that or tried to enable CPU Address Pipeline Mode. Essentially any tweaks I do in the BIOS at the moment make my system unstable
- his board does not POST with cache switched to write-back mode. Mine does, and actually offers two "adaptive write back" modes as well, not sure what they are
- I get almost two times the memory bandwidth (79.71 MB/s vs 45 MB/s)
Currently it runs Quake at 20.7 FPS (timedemo demo1) and at 22.1 FPS with Voodoo (640x480). Weirdly enough it feels very playable, but it does stutter a bit whenever there are explosions on the screen or other effects that generate a lot of particles.
Descent 2 framerate really jumps from 40 something to 27FPS but still feels very playable (the Voodoo version is almost unplayable). Duke Nukem 3D doesn't really go below 30FPS, the actual framerate of course depends on the scene (outdoors/indoors, etc). Doom timedemo gives 1682 realtics (44FPS).
So far, the system gives a pretty nice experience in most games of the era, but it does feel like Pentium 100 performs a lot worse than it should.
Compared to mpe's benchmarks on 430FX I can see that P100 performs on the Supermicro somewhere between P75 and P90! And it only gives a slight edge over AMD 5x86 and only in some cases. No wonder these board weren't too popular! Right now it feels a bit like a 486 board with a Pentium Overdrive (which it kind of is).
I'd like to upgrade the BIOS to the latest version 3.2, but for some reason the amibios upgrade procedure (hold Ctrl+Home before you turn the machine on until it starts to read the ROM file from the floppy) doesn't work. I've decided to finally buy a TL866, so I'll try to flash a new BIOS then. Hope it will allow me to tweak cache/RAM timings.
I will also try to get my hands on a WinChip IDT C6 chip. WaybackTech scored 17.7FPS with it in Quake and 21.4FPS wih P-MMX@166 which kind of makes me hope that my motherboard is less of a bottleneck than his is (I do have almost twice the memory bandwidth after all).
Oh, and I hope to restore my other S5/VLB motherboard using an Opti Python chipset, but I'm yet to figure out all the missing resistors.