So P55 can't do a video card + physx+ audio?

[Bojamijams]

Since the P55 chipset only has 20 pci-e lanes

GPU: X16
PhysX: X4
Sound Card = ....?

Am I getting that right? Seems.. odd.

[MpG]

I believe the PCH can provide up to 8 PCI-E lanes, although they're only at first-gen speed, which is why Nvidia wouldn't certify them for actaul graphics usage, only PhysX. So as long as the mobo maker has provided the slots, you could give four lanes to a Physx card, and still a couple left over for sound, NIC, etc.

[Zero82z]

I believe that LGA1156 CPUs have 16 lanes, and the P55 PCH will have 8. However, the specific lane allocation will depend on the board, so you may end up having to run 8x/8x/1x for the video card, PhysX card, and sound card respectively, or you may be able to run 16x/4x/1x.

[Bojamijams]

Oh I see so its actually 24 lanes not 20? Thanks :)

[Zero82z]

I thought it was 4, but according to Wikipedia the P55 PCH has 8 PCI-E 2.0 lanes. I'm actually not 100% sure on that number, so it could still turn out to be 4, in which case the configuration would be 8x/8x/1x.

[MpG]

Originally Posted by Bojamijams

Oh I see so its actually 24 lanes not 20? Thanks :)

Disclaimer: As best I understand it. There's been a number of claims put out, but this seems to be the most reliable one. There seems to be a little term-fudging as well, as the lanes provided by the PCH are apparently "PCI-E 2.0 compatible", but they actually only run at first-gen speed. So you can plug a 2.0-spec device into them, but it's only going to get 1.1-spec bandwidth. Perhaps that's not an issue with PhysX, but it helps explain why Nvidia won't support Tri-SLI on triple-slot P55 motherboards, just SLI+PhysX.

[Chilly]

Sigh... Alright, let me clear this up, the i5/i7 LGA1156 chip has x16 PCIe 2.0 lanes, now the P55 chip is connected to the CPU via a DMI link, which is the equvilent of a 4x PCIe 1.1 link.

So the "20" lane figure is CORRECT, as this is by how many lanes the CPU has access to. HOWEVER, the P55 chipset has by itself a certain amount of PCIe lanes it can give out, BUT this does not increase overall system bandwidth as it must be compressed down to fit the DMI link(4x PCIe 1.1) anyways. Until Intel releases the P55 chip, there is some conflicting information on how many PCIe lanes the PCH will actually have to give out, but I can guarantee that it will have *at least* 6x PCIe 1.1 lanes.

So just to clarify, the PCH(P55) could have 1,000,000,000,000x PCIe 2.0 to give out, but it doesn't change the fact that it still has to communicate all that via the sole DMI link which has the equivalent bandwidth of a 4x PCIe 1.1 link. Hence, the i5/i7 LGA1156 CPU's can be said to only have 20x PCIe lanes to communicate with.

Having said all that, don't worry too much, there's plenty reasons why one might want to go with X58 based system vs a P55 system, but you'll be able to plug more than just 1 graphics card and a physx card in a P55 system. There are solutions out there(such as PCIe lane splitters, ala the NF200 chip) that will allow folks to plug in everything they want into a P55 based system, bottleneck issues aside.

You'll be able to have your Dual GPU+PhysX+Audio on P55 and have it work just fine, the real question will be, will there be any bottlenecking+performance issues or not, and if so, how major/detrimental are they.

[Bojamijams]

Well thats the thing and I guess until we get some numbers on the 5870 (and later the G300) we won't know if a single GPU can actually even use 8x speed.

But whats worrying me is this 1.1 lane speed. Does the PhysX need 2.0 or is 1.1 enough? For audio cards I assume 1.1 is plenty

It doesn't seem very future friendly this 1156 platform.

[Chilly]

Originally Posted by Chilly

<snip>Until Intel releases the P55 chip, there is some conflicting information on how many PCIe lanes the PCH will actually have to give out, but I can guarantee that it will have *at least* 6x PCIe 1.1 lanes.</snip>

Taken from HWC's review

I was correct, well, mostly, ended up that the PCH(P55) has 8x PCIe 1.0 links instead of only 6x. Everything else I have been saying about P55 and LGA1156 also turned out to be correct, such as the P55 being connected to the CPU via a DMI link with the equivlent bandwidth of a 4x PCIe 1.0 link. My advice/information stays relevant.

Not that P55, LGA1156, and the i5/i7 brand have been a well kept secret though!

[JMCD]

Originally Posted by Chilly

You'll be able to have your Dual GPU+PhysX+Audio on P55 and have it work just fine, the real question will be, will there be any bottlenecking+performance issues or not, and if so, how major/detrimental are they.

This is exactly what I'm looking at right now, as I see an upgrade in my near future. i5 or i7, I sure like the cost difference though!