is 64 bit pci card in a 32 bit pci slot possible?

Xamindar · Post by **Xamindar** » Thu Apr 14, 2005 11:46 pm

Ok, here's the situation. I have a scsi raid controller that has a 64 bit pci interface (about twice as long as a normal pci interface). I want to use it in a computer which only has 32 bit pci slots, which is the case with most computers. Would it be able to function like this?

Currently I can't get it to be happy with any of the ram I have tried to put on it so I'm wondering if this could have something to do with it.

fliptw · Post by **fliptw** » Fri Apr 15, 2005 12:05 am

CDN_Merlin · Post by **CDN_Merlin** » Fri Apr 15, 2005 12:30 am

(about twice as long as a normal pci interface)

This alone should tell you it wouldn't work. HTF would youfit it in the slot to start with?

BUBBALOU · Post by **BUBBALOU** » Fri Apr 15, 2005 5:35 am

64slot to 32card is usually backward compatible and vv, in your case -- 64card to a 32slot. I hope you did not fry anything they card and slots are keyed differently for 3.3V(32)and 5V(64) operation

Xamindar · Post by **Xamindar** » Sat Apr 16, 2005 1:38 am

Ok, well. It turns out that 64 bit cards ARE backwards compatable with 32 bit slots(of course, as long as there isn't anything else in the way of the extra length of the board). The card's performance will just be degraded to 32 bit. I finally found a stick of ram that this controller supported and it is happily working in my 32 bit pci slot.

I ended up finding a web site that explained all this. Bubb, telling the difference between 3.3v and 5v on pci cards and slots is just as simple as looking at the notches on the card. A notch on one end signifies 3.3v while a notch at the other end signifies 5v. If the card has both notches (this raid card does) then it will support either voltage. I never realized that pci is so well thought out. So it is near impossible to insert the wrong voltage card in the pci slot as the notch will prevent it from going in.

BUBBALOU · Post by **BUBBALOU** » Sat Apr 16, 2005 7:27 am

yes I know all that, but really did not want to go into detail... most of them are some are not