Will a PCIe x16 card work in a PCIe "electrically" x4 slot?

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kastachu

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I currently have a P5K Deluxe with an EVGA 8800 Ultra occupying the "main" x16 PCIe slot. I'm looking to purchase a secondary card to drive two other LCD's over DVI-D; however, I'm a bit confused regarding PCIe x16 cards. That is, every single 8-series card seems to be "x16", whereas the remaining slot on P35 motherboards is a x16 slot (that is electrically a x4 slot).

Basically, I'm wondering if an 8-series card will even function in a "fake" x16 slot (since it's electrically only a x4 slot) or if I'm required to purchase a x1-x4, or plain PCI video card.

Thanks!
 
From the specifications on the P5K Deluxe:

PCI Express x16
2 x PCI-E x16 (blue @ x16 mode, black @ x4 or x1 mode)

It is an x16 slot, it's just in x4 or x1 "mode". Anyone know for sure if a 8-series x16 card (such as the 8500 GT) will function correctly in the secondary x16 (x4/x1) slot? Thanks!
 
I'd appreciate information on this too. My motherboard has the same thing, labeled (PCI Express x16 Slot (electrical x4), and I have no idea what it is for.
 
Yes it will work, the 965 boards are the same way. Both boards also support crossfire as well, meaning two cards have to work in it. Original SLI boards and 975 boards only offered 8x bandwidth to both slots at the same time, you should be fine. You can even use a PCIe 16x card in an open ended 4x slot.
 
Yah, but why buy another 8 series card for a secondary vidcard?!?! I guess it would be good if you plan to use it for HD decoding. Otherwise, get a cheap $30 card instead.
 
enginurd said:
Yah, but why buy another 8 series card for a secondary vidcard?!?! I guess it would be good if you plan to use it for HD decoding. Otherwise, get a cheap $30 card instead.
Click to expand...

I'm mostly worried about driver compatibility issues with Vista 64 and running different series of video cards. Reference posts: here and here.

I PM'd Hotdog453 who replied with his solution to getting the 8800 and 8500 to work together to drive three LCD's in Vista 64: he ditched his 975x board and got a 680i board instead, which resolved his problems. A bit extreme in my opinion and I'd rather avoid having to purchase a new motherboard just to reliably run the extra two LCD's.

silent-circuit offered his tip of using an older series card with modded INF drivers; however, he is not running the mentioned configuration (64-bit Vista, 3 LCD's, two mixed video cards) so his recommendation is more based off his success with running a 6-series laptop card with the modded INF drivers.

Also, the price difference between the lowest end 6/7/8 series cards that have two DVI outputs seems to be in the neighborhood of $20-30. I figure I might as well go for an 8-series in hopes for less issues with drivers.
 
Isn't Kyle running an 8 series card with a 6 series card? not sure if its in Vista 64 though. In any case, I see your concern.
 
enginurd said:
Isn't Kyle running an 8 series card with a 6 series card? not sure if its in Vista 64 though. In any case, I see your concern.
Click to expand...

Did a little research, unfortunately, Kyle is running WinXP.

However, could it possibly just be an issue of P35 boards not enjoying having two NVidia x16 cards in them? The PCIe 6 series card that Kyle uses doesn't seem to be a x16 part, though I'm not completely sure. If that is the case, I might be shooting myself in the foot by trying to get another 8 series card to play along with my 8800 Ultra; instead, I should be looking for a 6 series that is rated at x1 or x4 or however that works. Also, I don't think I've seen a single sig that lists a system with two non-SLI'd 8 series cards running on a P35 board; this only further fuels my growing conspiracy theory.

Needless to say, I'm at a bit of a loss on what to do here.
 
The 6 series were all PCIe 16x, they were not 8x or 4x, although they are compatible since the PCIe spec says they have to be. I've run an X1950XTX and X850XT in a gigabyte 975 board in vista for 3 monitor support. It has both slots at 8x, I even through a X600 in on of the 4x slots that runs a 2x and it ran as well. As long as nVidia has unified drivers for their cards in Vista, there's no reason that they wouldn't work. The latest 162.22 drivers for Vista 32-bit support the 6, 7, and 8 series cards. You shouldn't have any problems running any combination of those cards in Vista with those drivers (provided nVidia actually provided working drivers).
 
Yes it will work. It's part of the PCI-E specifications. a PCI-E x16 (physical) will work in any pci-e slot. x1, x2, x4, x8, x16.
 
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