X79 and PCI-E 3.0

[xmanrigger]

This maybe old news to some, but I thought I would throw this out here. When I originally built my X79 system, PCI-E 3.0 was listed as a spec for the Asus RIVF. As well, PCI-E 3.0 was listed as a spec for my GTX680(s). However, it didnt matter what I set the BIOS to, or what video driver I used, I could only achieve PCI-E 2.0. I later discovered nvidia gimped the drivers to only run at 2.0 because of issues. Since then, I had discovered a patch to enable PCI-E 3.0 in Win7/8.
Reason for the post is I just did a fresh install and noticed I needed to patch the registry for PCI-E 3.0. I thought I would share this hack.

Searching, some articles will say there is no performance increase between PCI-E 3.0 and PCI-E 2.0 with a GTX680. Just to re-confirm, I played BF4 before and after the patch. Yes, at higher resolutions, there is a noticeable performance increase. I run 2560X1440 rez if that matters.

If running X79 and only PCI-E 2.0, you might want to check out the patch. Run it from a command prompt, reboot, and walla, PCI-E 3.0.

LINK http://nvidia.custhelp.com/app/answe...QvaDEzbE45X2s=

EDIT: I forgot to mention; you may see slightly higher GPU temps once running at PCI-E 3.0.

[Hooded]

Good bit of info thanks.

[Bartacus]

Well I'll be jiggered. I just fired up GPUZ on my main rig (x79), and it says PCIE 2.0 for my GTX980s. And SLI is disabled for some odd reason. Thanks Xman!!

EDIT: hmmm, I have 980s in Windows 10, and that patch only lists slightly older GPUs. Shouldn't I be PCIE3.0 without a hack?

[xmanrigger]

Well I'll be jiggered. I just fired up GPUZ on my main rig (x79), and it says PCIE 2.0 for my GTX980s. And SLI is disabled for some odd reason. Thanks Xman!!

EDIT: hmmm, I have 980s in Windows 10, and that patch only lists slightly older GPUs. Shouldn't I be PCIE3.0 without a hack?

Check and make sure you have it enabled in BIOS or if your mobo supports 3.0. You should see no adverse effects running GTX980s and patching. If you do, you can a add revert to the command line to set back to PCI-E 2.0.

Check your BIOS first to ensure PCI-E 3.0 is enabled prior to running the patch. If it is and still only running at 2.0, run the patch.

If you recently updated your video driver or never enabled SLI to begin with, that would explain why SLI is disabled. Driver updates usually put the card back to default settings.

[Bartacus]

Yeah, that explains a lot. Driver update reverted the SLI settings. Motherboard PCIE lanes are all set to Gen3 in the bios, but my CPU (3820k) only supports gen2, so this may all be a moot point.

[xmanrigger]

Intel states only 2.0 for my 3930K, but I can assure you, it is running at PCI-E 3.0

[Bartacus]

Is there any tangible performance benefit though? I can't see how. 5TB/s versus 8TB/s, and we're probably not even close to hitting any PCIE limits here. But then again I run at 4K, so every bit helps. Did you do any before / after benchmarking?

[xmanrigger]

Is there any tangible performance benefit though? I can't see how. 5TB/s versus 8TB/s, and we're probably not even close to hitting any PCIE limits here. But then again I run at 4K, so every bit helps. Did you do any before / after benchmarking?

I havnt run any benchmarks per say to compare. I did notice smoother and 'fluid' game play in BF4 though.

What mobo are you running? And can you do some before and after benches? I will see what I can muster.

EDIT: Maybe agree upon what bench to run so apples to apples kinda thingy.

[Bartacus]

I'm running an Asus Rampage 4 Gene, latest BIOS. That reg fix/hack scares me though, since I can't seem to Google up anyone who's done it on Windows 10.

[xmanrigger]

I'm running an Asus Rampage 4 Gene, latest BIOS. That reg fix/hack scares me though, since I can't seem to Google up anyone who's done it on Windows 10.

The patch is said to work with Win8.1 and Win10 as well. Just make sure you run the Command Prompt as Administrator (right click the icon) or the patch does nothing. (disable SLI prior to the patch. Enable SLI after patch and reboot)

If you are brave, do it manually this way: (disable SLI prior to the patch. Enable SLI after patch and reboot)

Enable it manually via regedit...

#1 Press windows key + r to bring up the run box.

#2 Type regedit and hit enter.

#3 Goto HKEY_LOCAL_MACHINE/SYSTEM/CurrentControlSet/Control/Video

#4 Identify the correct registry folders for each of graphics cards you have installed. There will be one associated folder for each card installed. To identify the correct folder for each card, you will need to review the names of each folder within the “HKEY_LOCAL_MACHINE/SYSTEM/CurrentControlSet/Control/Video” registry directory. The folder associated with a graphics card will have three or more subfolders (depending on how many PCI-E slots available on the motherboard). The values listed for each subfolder will be 0000, 0001, 0002, 0003, 0004, and Video. Review only the subfolders labeled as "0000". You will know you have selected the correct "0000" subfolder when you see a registry labeled “DriverDesc” with a value that matches the graphics card you have installed.

#5 Right click on the folder labeled “0000”. Select “New”, then select “DWORD (32-bit) Value“, then enter “RMPcieLinkSpeed” for the name of the registry.

#6 Right click the “RMPcieLinkSpeed” registry you just created, then select “Modify”, then enter “4” as the data value and verify that the “Hexadecimal” option is checked under “Base”, and then select “OK”.

#7 Repeat steps 5 and 6 for each graphics card associated folder (named “0000”)

#8 Once you have completed creating the RMPcieLinkSpeed registry for each card, close the Registry Editor window and restart your computer.

#9 Once your system is back into operating system environment, run GPU-Z and verify that the “Graphics Bus interface” value shows PCI-E 3.0 for each card.


How about Unique Heaven for a benchmark?

[Bartacus]

I wonder if there are any benchmark progs that can tell you PCIE bus usage? If you notice a smoothness improvement with BF4, that's more than enough evidence for me. What resolution are you playing at?

[xmanrigger]

I wonder if there are any benchmark progs that can tell you PCIE bus usage? If you notice a smoothness improvement with BF4, that's more than enough evidence for me. What resolution are you playing at?

My resolution runs at 2560X1440

NOTE: I attempted to revert back to PCI-E 2.0 using the patch and adding revert to command line. All indications were that it worked. But upon restart, still at 3.0. I was able to revert back to 2.0 by installing video driver. (I was behind a version)

I ran Heaven with PCI-E 2.0 and 3.0. You will see a noticeable bump on the Minimum Frame rates. It was enough to smooth out game play at 2560X1440. I used the 'Extreme' setting in Heaven 4.0.

PCI-E 2.0



PCI-E 3.0

[Bartacus]

Interesting stuff Xman, thanks for the info! If you see an improvement in windowed mode, you'd probably see a bigger gap if you ran it full screen at 1440p. I think I'll experiment a bit with this tomorrow at 4K and see what's up.

[xmanrigger]

Strange things going on. This was prior to the patch as well. Multiplier set at 46 and FSB at 103 should give me 4738mhz on CPU. Only ramping to 4326 mhz. I disabled Speedstep to get it to 4738. Anyways, I scored lower at 4738 than I did at 4326mhz. Go figure.

Did you get running at 3.0?

[Bartacus]

Nah, never tried yet. I had a bit of food poisoning, so I didn't do much today other than poop and feel miserable. I did a lot of reading up on this, and I'm not convinced it's really worth it for me, just because I haven't been gaming at all lately. I'll play with it tomorrow though, and see if there's any difference in some 4K benchmarks in Heaven at full screen.