64bit/66mhz pci slots

odog

Diamond Member
Oct 9, 1999
4,059
0
0
yeah i'm pretty sure...

i believe it's backwards compatible.... some 64bit 66mhz pci cards even fit in 33mhz 32bits slots, but have to run at slower speeds to cope with the bandwidth reduction.(example a U320 SCSI cards)
 

skriefal

Golden Member
Apr 10, 2000
1,418
3
81
No. 32-bit PCI cards require a 32-bit PCI slot... they won't even fit into a 64-bit 66MHz slot, since the slots are keyed differently. More precisely, a 32-bit slot will accept 32-bit cards operating at 33 or 66 MHz. A 64-bit 66MHz slot will accept 64-bit cards operating at 33 or 66 MHz. A 64-bit 33MHz slot will accept 64-bit or 32-bit cards operating at 33MHz.

There may be some 64-bit cards that are dual-keyed so that they can also operate in a 32-bit slot, however.
 

mastertech01

Moderator Emeritus Elite Member
Nov 13, 1999
11,875
282
126
From what Ive seen they are not. 66MHZ PCI slots have a different voltage requirement. 64bit 33mhz PCI slots are backwards compatible.
 

Rand

Lifer
Oct 11, 1999
11,071
1
81
No they are not compatible, their keyed differently and they operate on a different voltage. 32bit PCI cards definitely will not operate in a 64bit/66MHz PCI slot.
Most, though not all 32bit/33MHz PCI cards will run in a 32bit/66MHz PCI slot though.