Friday, March 23rd 2012

GeForce GTX 680 Release Driver Limits PCI-Express to Gen 2.0 on X79/SNB-E Systems

by
btarunr
 Discuss (39 Comments)
Users of systems running Core i7 processors in the LGA2011 package and X79 chipset motherboards will find that their GeForce GTX 680 will not run at PCI-Express 3.0 x16 mode, using launch drivers. This is because NVIDIA decided against implementing Gen 3.0 support for the new GPU on X79/SNB-E systems, at the very last moment. Pre-launch drivers, including the driver that ships on discs with the graphics cards, will let the GPU run at Gen 3.0 mode on some X79/SNB-E systems, however the post-launch stable drivers (such as GeForce 301.10 WHQL), won't.

The specifications page of GeForce GTX 680 on GeForce.com has been updated to mention this:
GeForce GTX 680 supports PCI Express 3.0. The Intel X79/SNB-E PCI Express 2.0 platform is only currently supported up to 5GT/s (PCIE 2.0) bus speeds even though some motherboard manufacturers have enabled higher 8GT/s speeds.
Sources in the PC motherboard industry we spoke with, confirmed this change. PCI-Express 3.0 x16, for now, might only run on upcoming "Ivy Bridge" Core systems, running on motherboards with PCI-Express 3.0 compliant components. NVIDIA could be working to fix the issue.

Update 3/23, 21:56
NVIDIA courteously responded to our article, with a statement. Here's the statement verbatim:
While X79/SNB-E is a native Gen2 platform, some motherboard manufacturers have enabled Gen3 speeds. With our GTX 680 launch drivers, we will only be supporting Gen2 speeds on X79/SNB-E while we work on validating X79/SNB-E at these faster speeds. Native Gen3 chipsets (like Ivy Bridge) will still run at full Gen3 speeds with our launch drivers.

GeForce GTX 680 supports PCI Express 3.0. It operates properly within the SIG PCI Express Specification and has been validated on multiple upcoming PCI Express 3.0 platforms. Some motherboard manufacturers have released updated SBIOS to enable the Intel X79/SNB-E PCI Express 2.0 platform to run at up to 8GT/s bus speeds. NVIDIA is currently working to validate X79/SNB-E with GTX 680 at these speeds with the goal of enabling 8GT/s via a future software update. Until this validation is complete, the GTX 680 will operate at PCIE 2.0 speeds on X79/SNB-E-based motherboards with the latest web drivers.
This statement confirms our assertions made in the article. NVIDIA's statement on the GeForce.com product page originally formed the basis of this article, which we pasted verbatim, while preparing the article. Motherboard manufacturers have extensively marketed their LGA2011 products as natively supporting PCI-Express Gen 3.0 (8 GT/s). What's more, the datasheet of Intel Core i7 LGA2011 processors (refer 1.2.2) clearly mentions the PCI-Express root complex as supporting 8 GT/s. AMD Southern Islands GPUs have supported PCI-Express Gen 3.0 on LGA2011 platforms since day one.

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39 Comments on GeForce GTX 680 Release Driver Limits PCI-Express to Gen 2.0 on X79/SNB-E Systems

#26
Aquinus
Resident Wat-man
mike_6289Probably not because there's less data
I don't think it is that much less...
Posted on Reply
#27
Jurassic1024
To create Kepler GeForce cards, nVIDIA removed a lot of the GPGPU components to separate it from the Quadro cards. Basically, with the 600 series, GeForce is more of a gamers GPU now than before.
Posted on Reply
#28
Badelhas
A little off-topic: what is the performance impact in a x8x8x4 SLI configuration?

Cheers
Posted on Reply
#29
Aquinus
Resident Wat-man
BadelhasA little off-topic: what is the performance impact in a x8x8x4 SLI configuration?

Cheers
Assuming that you're talking about PCI-E 2.0, I think it would be noticeable since the 7970 struggles with PCI-E 2.0 x8, let alone x4. Now PCI-E essentially doubles bandwidth, so x8 would be less of a problem, but the x4 would most likely still bottleneck. If you were planning on running GTX 680s in 3-way SLI, I wouldn't recommend it with that few PCI-E lanes.
Posted on Reply
#30
Badelhas
AquinusAssuming that you're talking about PCI-E 2.0, I think it would be noticeable since the 7970 struggles with PCI-E 2.0 x8, let alone x4. Now PCI-E essentially doubles bandwidth, so x8 would be less of a problem, but the x4 would most likely still bottleneck. If you were planning on running GTX 680s in 3-way SLI, I wouldn't recommend it with that few PCI-E lanes.
Yes, I was refering to PCI-e 2.0, but the cards would be GTX570. Same thing? Do you have any links where someone did benchmarks to comprove it? I ask this because I have a P8Z68-V Pro, that offically only supports x8x8 dual SLI, but it does have a x4 extra PCI-e...
Thanks again.

Cheers,
Posted on Reply
#31
Aquinus
Resident Wat-man
BadelhasYes, I was refering to PCI-e 2.0, but the cards would be GTX570. Same thing? Do you have any links where someone did benchmarks to comprove it? I ask this because I have a P8Z68-V Pro, that offically only supports x8x8 dual SLI, but it does have a x4 extra PCI-e...
Thanks again.

Cheers,
The x8 should be fine for the 570, but my concern would be the x4 slot. I'm not sure how well it will perform. Also SLI and Crossfire scaling at 3 GPUs isn't very widely supported. I would recommend just two 570 at the moment. You haven't filled in your current system specs, so I can't give too much of a recommendation, but if you're not running multi-monitors and not higher than 1920x1200, just two should work nicely.
Posted on Reply
#32
Badelhas
AquinusThe x8 should be fine for the 570, but my concern would be the x4 slot. I'm not sure how well it will perform. Also SLI and Crossfire scaling at 3 GPUs isn't very widely supported. I would recommend just two 570 at the moment. You haven't filled in your current system specs, so I can't give too much of a recommendation, but if you're not running multi-monitors and not higher than 1920x1200, just two should work nicely.
Thanks for your reply. I play mostly at 720p 3D Vision with a 88´´ Screen :)
I just filled my specs. Did you ever find any benchs of Sli in a x4 lane?

Cheers
Posted on Reply
#34
Badelhas
AquinusCheck this out, it's for a 480 but the results should be about the same: www.tomshardware.com/reviews/pcie-geforce-gtx-480-x16-x8-x4,2696-9.html
Thanks :)
But that test is for a single card in a x4 lane. Does this means only one of the cards in the Tri-SLI will be up to 20% slower or all of the cards will? I would like to find a benchmark or someone who tried Tri-SLI with one of the lanes at x4 speed so we would really know.

Cheers
Posted on Reply
#35
Erwinna
Help!

I need your help, oh wise ones. I would like the know if the GTX 680 card is compatible with my system (I am not really a techie so I am scouring the forums for some input). Here are my specs:

Core i7-2700K BX80619i72700K Unlocked Processor - Quad Core, 8MB L3 Cache, 1MB L2 Cache, 3.50 GHz (3.90 GHz Max Turbo), Socket H2 (LGA1155), 95W, Fan, Retail

GIGABYTE GA-Z68X-UD3H-B3 Intel Z68 Motherboard - ATX, Socket H2 (LGA 1155), Intel Z68 Chipset, 2133MHz DDR3, SATA 6.0 Gb/s, RAID, 7.1-CH Audio, Gigabit LAN, SuperSpeed USB

2 x HyperX Genesis 8GB DDR3-1600MHz CL9 Dual Channel Kit (2 x 4GB) w/ Intel XMP RAM
Sapphire (11179-13-20G) AMD Radeon HD 6870 1GB GDDR5 Video card

Corsair Force Series 3 120GB 2.5" SATA 6Gb/s Solid State Drive (SSD), Read: 550MB/s Write: 510MB/s, includes 2.5" to 3.5" bracket (CSSD-F120GB3-BK)

Seagate ST31000524AS Barracuda Hard Drive - 1TB, SATA 6Gbps, 7200 RPM, 32MB

Hydro H60 High Performance CPU Cooler
Corsair Professional Series 700 Watt PSU

Supports SATA 3 (6gb/s), USB 3.0, dual PCI-e slots for sli or crossfire setups. The mobo also has dual bios. 3.0, CrossFireX/SLI Ready.
Posted on Reply
#36
Aquinus
Resident Wat-man
ErwinnaI need your help, oh wise ones. I would like the know if the GTX 680 card is compatible with my system
I see no problem running one, a bigger power supply and you could run two in SLI with your platform. I would say if you're looking for a new toy, go ahead and have fun.
Posted on Reply
#37
Jurassic1024
ViperXTRhmm, if i remember correctly in the old bench of the HD 7900 series, impact of PCI-E 3.0 vs 2.0 has very little effect on gaming, but its noticeable on GPGPU tasks that requires massive amount of data to be delivered in the PCIE lane, i wonder if this cripples the GK104 more with its inferior GPGPU performance.
Why would it cripple it MORE THAN THE 7900'S if it's inferior? You know what inferior means right?
Posted on Reply
#38
Jurassic1024
BadelhasThanks for your reply. I play mostly at 720p 3D Vision with a 88´´ Screen :)
I just filled my specs. Did you ever find any benchs of Sli in a x4 lane?

Cheers
I remember my P5K-E had Crossfire support with two PCIe x16 slots. One was wired for x16, and the other being wired for x4 . If it was bad back then, and it was, it's no better now.
Posted on Reply
#39
Aquinus
Resident Wat-man
Jurassic1024I remember my P5K-E had Crossfire support with two PCIe x16 slots. One was wired for x16, and the other being wired for x4 . If it was bad back then, and it was, it's no better now.
I couldn't agree more. Next time try to not double post. If no one has posted, I recommend editing your last post instead of posting again. Thanks for your input. :toast:
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