@Corrie:
And SCSI works fine too? I remember some reports that up to 65MHz it was fine but over that caused SCSI errors or something. Well on the MKII most had a socket so it was way easy to overclock, just pop in a new 66MHz oscillator. I also heard MKII's were able to go to 80MHz more often than any other accelerator ever made!!!
I own a MKII and a GVP-m 4060, both OC. Well I am running at 60MHz on my MKII as it is in a 3000 and has no fan, and I have crappy SIMMS that cannot handle 66MHz. LOL But on my 4000 I have it at 66MHz and it works fine w/128MB Fast...