Just managed to get a silly little test system running with a Seanix Viper motherboard. We all know what OPTi's unlamented Viper chipset is, so no further introduction is needed here. As I have a soft spot for slightly less than usual motherboards and motherboard chipsets, of course I had to have an OPTi Viper chipset to go alongside my OPTi 82C295-powered Alaris Leopard system.
I noticed, however, that Seanix didn't fit a socket for a second TAG chip despite there being pads on the board for one, so I soldered in a socket and put a 32Kx8 SRAM chip on it.

Specs:
Motherboard: Seanix Viper, OPTi Viper chipset
CPU: Intel Pentium 90MHz FDIV, 60MHz FSB
RAM: 32MB FPM
Cache: 256KB async, two TAG chips fitted
Video card: Diamond Stealth 3000 PCI (S3 ViRGE/VX), 4MB

Benchmarks:
3Dbench 1.0C: 70.6
Chris 3D Bench: 103.8 / 32.0
PCPlayer 320x200: 22.6 640x480: 8.3
Doom min: 524 realtics max: 1456 realtics
Quake Mode13h: 21.3fps
Landmark: 940 / 1524 / 15123.69
Topbench: 255
Speedsys CPU: 66.30 Mem bandwidth: 149.92MB/s VGA: 13109KB/s

Fitting the second TAG chip didn't seem to do much of anything, Speedsys' scores remain the same with or without this chip fitted. Perhaps that is simply extra TAG space to cache larger memories? </hopeful>
Overall performance seems fairly in-line with the level of an Intel Mercury or Neptune chipset (except without the dysfunctional CMD640 or RZ1000 IDE controllers those frequently come with). For some reason the Viper doesn't seem to benefit from EDO memory much, you might as well just use FPM with it.

Pics will come later (will have to disassemble it again...)