PCI-E 3.0 not always enabled.

[Ericmopar]

I learned something recently.
After owning a MSI Z77A-GD65 mobo and a GTX 780, both of which are PCI-E 3.0, for 3 and 2 years respectively, I stumbled across something I didn't know.
PCI-E 3.0 isn't necessarily enabled, especially when talking about first generation PCI-E 3.0 products. (I've since learned this is problem going back to the GPU drivers of the vendors)

If you have a higher end GPU, I'd advise doing what I did and download GPU-Z and run it. You may want to click on the little question mark near the PCI-E box and run a test to see if your GPU is actually running at 3.0.

If it isn't running PCI-E 3.0 then you can do a registry hack to enable it.

I did the registry mod, not expecting much... boy was I wrong. I have way fewer instances of the CPU bottle necking the GPU.
Sherman Hill, a recent complaint of mine, is running much smoother now, even in crowded yards and in scenarios with the advanced weather like thunder storms.

Here's an article showing how.
Keep in mind that, any Nvidia driver update will undo this mod and a person will have to go back into the registry.
http://forums.evga.com/How-to-enable-PC ... 07292.aspx

[buzz456]

I can't get GPU-Z to run. It just keeps telling me it stopped working.

[Ericmopar]

Did you get it from here? This' the legit site.
https://www.techpowerup.com/gpuz/

You may have to right click it and click "Run as Administrator"
You may have to right click on the installer Buzz and "Run as Administrator"
Most things that have to do with PC vitals should always be installed and run as an administrator.

Note: I just realized I'm also running an older version 0.8.9.

[buzz456]

Got it works now. Thanks.

[Ericmopar]

I forgot to add, the numbers in the left end of the bus interface box are what it's capable of running at, but the numbers in the right side of the box indicate how many GPUs by what speed it's actually running at.

[peterhayes]

Eric
Good find.
My Haswell rig with a GTX 970 was already on PCIe 3.0 but my Sandy Bridge with a GTX 960 remains on PCIe 2.0 even with the registry hack, as I believe that SB mobos do not support PCIe 3.0?
Thanks again
pH

[Ericmopar]

Eric
Good find.
My Haswell rig with a GTX 970 was already on PCIe 3.0 but my Sandy Bridge with a GTX 960 remains on PCIe 2.0 even with the registry hack, as I believe that SB mobos do not support PCIe 3.0?
Thanks again
pH

Could be.
I started out with Ivy Bridge LGA 1155.

[trev123]

My motherboard supports PCIe 3.0 but my Intel Core i5-2500K Sandy Bridge Quad-Core 3.3GHz only supports PCIe 2.0.

[Ericmopar]

I finally got curious enough to look it up at the Intel Ark.
Ivy Bridge was the first Intel CPU series on LGA 1155 to support PCI-E 3.
At the time it came out, there apparently weren't any PCI-E 3 devices out yet to plug into the PCI-E slots.
That makes sense, since the Mobo would have to support it first, then the devices that can use it.

That kills me that I had to manually create the registry entry for it to work on my system...
In any case my Train Simulator is working much smoother now. So much for online theories that nothing can actually use PCI-E 3 capabilities yet.

[peterhayes]

Eric

That kills me that I had to manually create the registry entry for it to work on my system...

I'm surprised by that, but then I think that I set this in the BIOS when I installed the card - so that could be the reason why my GTX 970 was set on PCIe 3.0??
I've just checked my IVYBRIDGE PC with a GTX 750TI and that is automatically set to PCIe 3.0 x 16 as well.
Great find, however!
Regards
pH

[Ericmopar]

My BIOS doesn't have a setting for PCI-E speeds.
I learned that part of the problem on some systems, may be a need to select "I prefer maximum performance" in the NVCP.
Some people said the registry hack didn't work at first, until they changed that setting in NVCP. That's not true for everyone though.

[ssbobz]

On my system the pci-e for the gpu idles at 1.1 and switches to 3.0 under load.

[Ericmopar]

On my system the pci-e for the gpu idles at 1.1 and switches to 3.0 under load.

That's normal if PCI-E 3 is properly enabled. I have my Global power set up now for "Adaptive" and the game setting "I prefer Maximum Performance"
My PCI-E 3 wasn't enabled, although from some quick reading I think it's the first generation Mobos and Devices that have that little quirk of not always enabling 3.0 .