I had the chance to test several motherboards with the K6 and I can say that it ran on each of them flawlessly, even in case the BIOS wouldn't recognize the CPU. I've tried so far:
- Abit IT5H
- AOpen AX5T-1
- AOpen AP5T-2
- Asus P/I-P55T2P4 rev 3+
- Asus TX97
- FIC PA-2011
- Tyan S1570 (today!!)
I have to differentiate the results between good Windows 95 and good Windows NT performers. The fastest board under Windows NT was clearly the FIC PA-2011. This board comes with the VIA Apollo VP2 (VT82C590) chipset, which is already well known under the name AMD 640 now. The difference wasn't big, but definitely noticeable.
Under Windows 95 the fastest board was the Tyan S1570 TitanTurbo, which is the last one I've tested. The differences are not big though and I can say that except of the Asus P/I-P55T2P4 all boards were within 1.5 Winstone points. The T2P4 however didn't have a BIOS that recognized the K6, which means that the 'write allocation' wasn't switched on and I think this was the reason for its worse performance.
Now the funny thing is that the Pentium MMX is not running fastest on the FIC board as well. I haven't found a reason why yet, but it's kinda remarkable. The Pentium MMX is still running best on a TX board for Windows NT and on the IT5H for Windows 95.