Nvidia's answer to x79 and PCI-e 3.0

[jezjohnson]

Looks like Nvidia are no longer trying to support PCI-e 3.0 on x79. They have just posted an exe file to enable it

excerpt from nvidia tech:-

"GeForce GTX 680 and GTX 670 GPUs support PCI Express 3.0. They operate properly within the SIG PCI Express Specification and have been validated on multiple PCI Express 3.0 platforms. Some motherboard manufacturers have released an updated SBIOS to enable the Intel X79/SNB-E PCI Express 2.0 platform to run at up to 8GT/s bus speeds. We have tested GeForce GTX 680 and GTX 670 GPUs across a number of X79/SNB-E platforms at 8GT/s bus speeds, but have seen significant variation in signal timing across different motherboards and CPUs. Therefore we’ve decided to only support and guarantee PCI Express 2.0 bus speeds on X79/SNB-E with our standard release drivers. Native PCI Express 3.0 platforms (like Ivy Bridge) will run at 8GT/s bus speeds with our standard release drivers.

Though we cannot officially support or guarantee 8GT/s speeds for X79/SNB-E, you can manually enable faster 8GT/s bus speeds (at your own risk) on GTX 680 or GTX 670 GPUs using the following executable: force-enable-gen3.exe

If you would like to revert back to 5GT/s bus speeds you can do so by running the following command from the DOS command line: “force-enable-gen3.exe –revert”

You will need to reboot your system for the changes to take effect.

Click here to download force-enable-gen3.exe"

Bit of a cop-out really as ATI cards seem to work at PCI-e 3.0 fine......

[Arne Saknussemm]

What is going on here? My Rampage IV extreme is advertised as PCIe 3.0....Intel advertises X79 boards as PCIe 3.0 AMD has no trouble advertising their cards as PCIe 3.0.

What is the source of the "significant variation in signal timing" the CPU? Is SBE not PCIe 3.0

I'd like some answers from someone. Maybe asus would like to comment on thier implementation of x79 and their confidece that the problem is not theirs so I can seek explanation from someone else by elimination?

[Zka17]

It would be nice from Nvidia to specify those signal variations... which board/CPU combinations were the best and which of them was weak... In mean time, Asus could test it's own products (mobos and VGAs) and make the results public...

[Praz]

This announcement is not totally unexpected since Intel does not officially support PCIe 3.0 on Sandy Bridge-E processors. Seems to be the easy way out for nVidia. Perhaps one of the signaling issues nVidia is referencing is the Sandy Bridge-E errata below.

PCI Express* Gen3 Receiver Return Loss May Exceed Specifications

[jezjohnson]

x79-block-diagram.jpg

This announcement is not totally unexpected since Intel does not officially support PCIe 3.0 on Sandy Bridge-E processors. Seems to be the easy way out for nVidia. Perhaps one of the signaling issues nVidia is referencing is the Sandy Bridge-E errata below.

This shows 8GT/s which is PCI-e 3.0 on the LGA2011.....

[Praz]

Below is from the processor's datasheet. Notice how Intel differentiates between supported and capable?

Support for PCI Express* 2.0 (5.0 GT/s), PCI Express* (2.5 GT/s), and capable of
up to PCI Express* 8.0 GT/s.

[Arne Saknussemm]

Intel's x79 motherboards are advertised PCIe 3.0 http://www.intel.com/content/www/us/...rd-dx79si.html

How can this be if the 2011 CPU is not PCIe 3.0

The Intel data sheet throughout says chip is capable of up to 8.0 GT/s. and it meets PCIe 3.0 spec.

Nvidia don't mention the GTX 690 is it PCIe 3.0 on X79? If so how come 680 and 670 aren't?

One of either Nvidia or Intel or some motherboard mfrs don't have PCIe 3.0 but are selling as if they do. I would like to know which....

[jezjohnson]

I have now had a chance to try the exe file on Windows 8, must be different than the hack as adding the reg entry caused a black screen instead of login.

This exe works fine, shows up in Nvidia control panel as PCI Express x 16 Gen 3 and also in GPU-Z

At least it works ok on the RIVE

Happy as can be....

[xeromist]

Since he won't do it, I'd just like to say on Raja's behalf "I told you so". I say this not to be mean, but people were giving him a hard time last year because vendors were marketing 3.0 and he said they were wrong. And now Nvidia agrees that you can't just slap a 3.0 sticker on something and call it compliant.

Until the lane switch specifications and compliance is fully established anything plastered on boxes at this point means nothing. The impact of the older switches on PCIe 3.0 hasn't even been made public. And there are NO PCIe 3.0 GPUs to test the slots with and ascertain the actual bandwidth compliance.

[Terminal Meltdown]

I am disappointed that I have to manually use a reg hack to enable Pci-e 3.0. Who is to blame for the non-sense?