A mate who has a Dell XPS 630 is wondering this. It's based on an nvidia 650i chipset which has 2 16x pci slots, but each slot only has 8 lanes. And whatever way the bios is tweaked on this board, the lanes don't combine into 16 if you use just a single slot. Now I know from reading reviews that even 8 lanes on a single slot are not maxed, unless you run 2 cards in sli at 2500x1600 and use 32x SLI AA. And I also know this from work where the chaps in the know showed me this on a PCIe bus analyser. 8x is sufficient for any single card. So I assume when nVidia insist on 16x, they mean the slot and not how many lanes you need. However, will this carry forward into the GX280 and 4870. Will 8x lanes on a single PCI-e 1.0 slot be enough to get maximum potential out of these cards ? And I am talking about just running one of them. Not sli. Or is it too early to say ? The reason I ask all this is because his system is upgradable but no point in changing a very stable 650i board which overclocks decently enough if he is not interested in ddr3 or sli or crossfire. Just the fastest single card is all he wants next month. Right now he is using 2x8800gt's in sli. And it peforms well in everything. But a single card would be less noisy under load, and free up some valuable room so he could ad say a TV Tuner card, or a Raid card etc..
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Will the GX280 or 4870 need 16x PCI-e lanes
- Thread starter Flanno
- Start date
That's really strange behaviour for the motherboard to not want to do 16x PCI-E with a single card 
Sure that the board doesn't use the older SLI system with a switch card in between the two slots? Perhaps it's just a limitation with the board. Perhaps look about for a BIOS update for the board?
Anyway, as far as I'm aware there hasn't been any information that suggests that the next gen cards won't work in PCI-E 8x mode. Best just see how people get on running GTX 260/280's and HD 4xxx cards in Multi GPU configs on boards that are limited to 8x/8x.
Sure that the board doesn't use the older SLI system with a switch card in between the two slots? Perhaps it's just a limitation with the board. Perhaps look about for a BIOS update for the board?Anyway, as far as I'm aware there hasn't been any information that suggests that the next gen cards won't work in PCI-E 8x mode. Best just see how people get on running GTX 260/280's and HD 4xxx cards in Multi GPU configs on boards that are limited to 8x/8x.
That's really strange behaviour for the motherboard to not want to do 16x PCI-E with a single card
It's the way the board was designed between Dell and Nvidia (or that's what the official word is). Lot's of people on the Delltalk forums complaining about this. Personally I think it was just an error from the start, and a bios update might solve it. None available, not even in beta. However it makes zero diffeence to performance on current cards. On future ones, who knows I suppose.
Thanks
Unfortunatley this board just uses the standard bridge to connect 2 cards when in sli. And no jumper to be seen anywhere when running a single card to force it to use 16x lanes. Thanks.
I have a 650i and it has the little card you switch around. I assume the OEM version doesn't then. Ouch.
Either way I think the most performance loss you'd get would be around 2-3%. From benchmarks there's usually a 1% loss with current cards. Even a 4X slot only loses 5%.
Either way I think the most performance loss you'd get would be around 2-3%. From benchmarks there's usually a 1% loss with current cards. Even a 4X slot only loses 5%.