enough bandwidth on PCI-E slots for sli/xfire on new P67 sandybridge boards?

3t3P

3t3P

3t3P

Soldato
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Aye, with x8x8 you will be fine with SLI.

However, make sure you go for a P67 board that does proper x8x8, as all of the cheaper ones only do x16x4- which isn't ideal.

This is the cheapest proper x8x8 AFAIK (very good price with the rebate). The lowest ASUS board with this is the P8P67D PRO and for Gigabyte it is the UD4.
 
cheers my man:)

I'm good to go then

yeh i'm really eyeing up the asus PRO board, will look really nice in my current build.

The MSI is not to be scoffed at either, though i've only EVER used ASUS boards...

Might be time to go MSI, i'm liking the military class malarchy, even if its all FAKE, its working well on my MSI GPU:D

I'll wait till the dust settles and niggles have been ironed out
 
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No need for 2 x16 lanes of PCIe. There are plenty of reviews around that show no difference in performance against 2 x8 lanes.
 
depends on the cards being used tbh, but with 470's you should be fine.

edit: doesnt Sandy Bridge only have 16 lanes on the CPU anyways?
 
Stryda09 said:
I am pretty sure SB only supports 16x or 8x8x.
http://images.bit-tech.net/content_images/2011/01/intel-sandy-bridge-review/p67-blockdiagram.jpg
Click to expand...

Normally no but the P67A-UD7 has an additional NVidia NF200 chipset which supports up to triple SLI.

http://www.overclock.net/intel-motherboards/887761-p67a-ud7-most-depth-preview-review.html said:
NF200 takes the native 8 lane 5GT/s bus and doubles the bandwidth to 16x5GT/s so you would have 32 lanes of 2.5GT/S PCI-E bus for 16x SLI. Do not be fooled it doesn’t add PCI-E lanes; instead it splits the ones already present and adds bandwidth.
Click to expand...

That sounds like witchcraft to me but it seems to work. :p
 
Ch3m1c4L said:
depends on the cards being used tbh, but with 470's you should be fine.

edit: doesnt Sandy Bridge only have 16 lanes on the CPU anyways?
Click to expand...

580's still don't churn through enough data to choke 8x + 8x lanes, so no it doesn't depend on the card as the technology to bottleneck it isn't there yet.
 
The writer of that article is a bit off base. The NF200 doesn't 'double the bandwith'. It can't, as the CPU has 80GT/s of PCIe bandwidth (16x5GT/s) and that it, there is no more. What is does is permit lane configurations other than the 8x/8x and 16x/4x supported by the CPU.

Doing something like 8x/4x/4x with three slots needs a bridge chip like the NF200. Unfortunately, marketing being what it is, too many board manufacturers will run 32 PCIe lanes from the slots to the NF200 (32 is the maximum the chip supports) and advertise their board as 16x/8x/8x or something like that, even though those slots have exactly the same bandwidth as an 8x/4x/4x layout.

Not saying it isn't a useful addition, but it doesn't add performance, only flexibility. And because it adds latency to the PCIe bus and NF200 board will generally be a little slower with two graphics card than one running a pure 8x/8x configuration direct from the CPU.
 
I read somewhere that 295's were reaching the limit of pci-e 1.1 16x, ala pci-e 2 8x, so i assumed that would stand true with 580's. Unless it was simply hear say or someones guess, or maybe just theoretical max usage or something that I read ages ago.
 
yea, what i read was probably wrong, i didnt research it, was just something i read when i was reading reviews etc. As long as Loko knows what hes talking about that is, and isnt just making it up lol, but I assume he does :D
 
Well the Pro board supports Quad crossfire - so It should work with your 5970 + 5870.

As for bottlenecking the card - this review suggests that performance will be affected when running in x8 mode and under heavy stress.

May I ask why you bought a sandy bridge - when you already have an X58 system and you run a 3 GPU setup?
 
cmndr_andi said:
Well the Pro board supports Quad crossfire - so It should work with your 5970 + 5870.

As for bottlenecking the card - this review suggests that performance will be affected when running in x8 mode and under heavy stress.

May I ask why you bought a sandy bridge - when you already have an X58 system and you run a 3 GPU setup?
Click to expand...

In the real world it makes no odds. Out of all those tests one item was 18% hit and the others were 2 to 3%, which is what is typically seen. I don't class the latter as affecting performance.

Nevertheless, that is for a single card, I believe we were talking dual GPU. In SLI 16x to 8x lanes makes no difference.
 
On my i7 rig i run the 5970 in the x16 and the 5870 in the x8 because if i use both the x16s the cards are very close and run hot.

i benched marked using x16 and x8 and got same scores so had no hit what so ever with the 5870 in the x8 but with my new sandy bridge i might get some limiting not sure yet.

This is how close the cards are when i used both x16 slots on my gigabyte http://sites.google.com/site/ayupfromdik/files/5970.jpg?attredirects=0&d=1
 
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