Do 32-Bit cards work in a 64-Bit slot?

[BD231]

A few 64-Bit PCI questions:

1.) Do 32-Bit cards work in a 64-Bit slot (looking to add a video card, ide controller and sound if possible)
2.) If 32-Bit cards don't work in a 64-Bit slot, where can I find a 64-Bit compatible video card+ide controller?

Thanks guys!

 

[Chaotic42]

Yes, but it will slow everything on that bus down to 32 bit/33MHz.

Edit: It won't make it 32bit.

 

[Pariah]

They will work in 64bit 33MHz slots, very few work in 64bit 66MHz slots. They will not slow down the 64bit 33MHz slots and turn them into 32 bit slots. If by chance the card does work in 64bit 66MHz slots, it will slow the entire bus down to 33MHz, again, not dropping the other slots to 32bit.

 

[TerryMathews]

Also worth noting that some 64 bit slots support 'legacy' PCI cards, the 5V signaling cards that are common. These typically are the 33MHz variety.

The 64/66 slots, like those found on the 760MPX based boards do not support legacy cards and only work with 3.3V signaling. Cards based on the PCI2.2 spec support this.

Most 32/33 cards you can buy today are still PCI2.1.

 

[Chaotic42]

Originally posted by: Pariah
They will work in 64bit 33MHz slots, very few work in 64bit 66MHz slots. They will not slow down the 64bit 33MHz slots and turn them into 32 bit slots. If by chance the card does work in 64bit 66MHz slots, it will slow the entire bus down to 33MHz, again, not dropping the other slots to 32bit.

Yep, you're right about it not reverting to 32-bits. It will slow down the 66MHz bus to 33 though. I've tried 4 or 5 32/33 PCI cards in my 64/66 bus and they worked well.

 

[Bovinicus]

Yes, it should work. The only way to find out is to try. You can't damage anything by plugging a 32-bit card into a 64-bit slot.

 

[BD231]

So in effect dropping to 33mhz kills the 64-bit badwidth though right?

 

[InlineFive]

Originally posted by: BD231
So in effect dropping to 33mhz kills the 64-bit badwidth though right?

It cuts the bandwidth by half because of the 50% speed loss so yes.

 

[TerryMathews]

Originally posted by: Bovinicus
You can't damage anything by plugging a 32-bit card into a 64-bit slot.

Yes, you can but it's a long shot. Some (cheap) manufacturers like Koutech are making PCI2.1 (5V signaling) cards on PCI2.2 (3.3V) PCBs. Plugging a 5V card (32/33) into a 3.3V (64/66) slot is akain to plugging a 3.3V (2x AGP) card into a 1.5V (4x/8x) slot. If there isn't current overload circuitry in place, you stand the chance of blowing both card and board.

Originally posted by: PorBleemo

Originally posted by: BD231
So in effect dropping to 33mhz kills the 64-bit badwidth though right?

It cuts the bandwidth by half because of the 50% speed loss so yes.

32/33 = 133MB/sec
64/33 = 266MB/sec
32/66 = 266MB/sec
64/66 = 512MB/sec

 

[Pariah]

Plugging a 5V card (32/33) into a 3.3V (64/66) slot is akain to plugging a 3.3V (2x AGP) card into a 1.5V (4x/8x) slot. If there isn't current overload circuitry in place, you stand the chance of blowing both card and board.

You can't do that. 3.3V slots and 5V slots are keyed differently, so you can't install a standard 5V PCI card into a newer 66MHz 3.3V slot. 64bit 33MHz slots are 5volt which is why they are backwards compatible with standard 32bit cards.

 

[TerryMathews]

Originally posted by: Pariah

Plugging a 5V card (32/33) into a 3.3V (64/66) slot is akain to plugging a 3.3V (2x AGP) card into a 1.5V (4x/8x) slot. If there isn't current overload circuitry in place, you stand the chance of blowing both card and board.

You can't do that. 3.3V slots and 5V slots are keyed differently, so you can't install a standard 5V PCI card into a newer 66MHz 3.3V slot. 64bit 33MHz slots are 5volt which is why they are backwards compatible with standard 32bit cards.

You obviously didn't read my whole paragraph. Some (cheap) manufacturers are making cards on PCBs that are universal (PCI2.2 or 3.3V compliant) but the design is legacy. I've got a USB2.0 Koutech card that is cut universal but it still blew an A7M266-D when I plugged it into a 64/66 slot. Because it draws 5V.

 

[Pariah]

PCI 2.2 does not mean 3.3V, nor does PCI 2.1 mean 5V. PCI 2.1 supports 3.3V, PCI 2.2 is the first standard to require support.

Looking at Koutech's website, they only have one USB card keyed properly for 3.3V compatibility and it has 2.2 PCI listed in the specs. Every other card is not and all but one is specified as 2.1 PCI compliant. Your problem sounds like bad luck, not something Koutech did wrong.

Koutech USB

 

[TerryMathews]

Originally posted by: Pariah
PCI 2.2 does not mean 3.3V, nor does PCI 2.1 mean 5V. PCI 2.1 supports 3.3V, PCI 2.2 is the first standard to require support.

Looking at Koutech's website, they only have one USB card keyed properly for 3.3V compatibility and it has 2.2 PCI listed in the specs. Every other card is not and all but one is specified as 2.1 PCI compliant. Your problem sounds like bad luck, not something Koutech did wrong.

Koutech USB

PCI2.2 introduced the universal connector. The universal connector is supposed to indicate 3.3V compatability. I didn't think I needed to spell out each individual step.

I had a long conversation with Koutech's tech support. Although the card is keyed for PCI2.2 and 3.3V compatability, it is not 3.3V compatible. I can forward you the e-mails if you like.

There are a couple more cards out there. 2cpu forums is a good place to look, since the 760MPX userbase is the largest 'tinkerer' userbase of 64/66 boards out there. I seem to recall a 10/100 lan card that was keyed incorrectly, but the manf. escapes me.