A word of warning regarding GEN3 support and SB-E.

[Nodens]

I've been working a lot on my work projects these last few days and while profiling my own game engine, I noticed something that I think everyone here should know. GEN3 support MAY seem that it is working properly on your rig and it is actually NOT!

In my particular case, it seemed to work fine but while profiling my engine I saw what seemed like the display driver stalling every now and then. I immediately thought it was a driver problem and discarded it because it did not seem to have much of an effect in terms of performance. Then the new Neverwinter game launched and I decided to give that a spin since I had played its beta and I liked it a lot. Using the 320.00 driver, I noticed the game, with SLI on, would actualy start to lose frames and after a while become unplayable.

Cryptic's developers have included a very nice feature. Instead of an fps counter you can type /fpsgraph 1 and see an actual fps graph instead, where it became apparent that the driver was getting a huge number of stalling spikes that it obviously did recover from but it caused the framerate to gradually drop. SLI made it more intensive and the higher the image quality settings, the faster it manifested.

Since a few days had passed I did not immediately relate the two incidents, it took me like two days to investigate this further and tie them together. So I tweaked my own code and did some further testing and apparently this is entirely due to the GEN3 signaling. It may seem that's it's working right but it is not , even when it works. Apparently the nvidia driver does a very good job recovering from it BUT in certain conditions the issue WILL produce framerate drops and in theory it may freeze the PC. Yes, even if it seems to be working properly. This has managed to "hide" in my rig for QUITE a while. It was not apparent in any game or with my own code and if I had not decided to play Neverwinter, I wouldn't find out until MUCH later in my engine's development cycle.

I do not have time to pull out the AMD cards from the AMD testbed PC and test them on the X79 but in theory there should be no difference at all.

As of these tests, I do not believe that there's ANY case of a video card that works properly with GEN3 and SB-E. Only cases where the issues are masqueraded and from now on I am going to suggest to everyone to not enable GEN3 on this platform until you have an Ivy Bridge-E CPU.

[HK-47]

I have been away from home all weekend. Just now starting to download the game. Is there any specific resolution/settings I should test with, besides Gen2 Gen3? Going to be about 35 min to download 😞 this speed bump to 90 Mbps can't happen soon enough with my ISP!

Also a maybe you can answer this Nodens, but why haven't I noticed this in any other games. I normally play with vsynch off and a fps cap of 65 fps on most games. Vsync doesn't seem to work correct running a mix of 2x Displayport and 1 DVI with crossfire enabled. I get bad stuttering. I am hoping the Displayport 1.2 MST hubs Accell will be releasing in the next 45-60 days will fix the vsync issue running eyefinity and trifire.

[Nodens]

HK-47 wrote:
I have been away from home all weekend. Just now starting to download the game. Is there any specific resolution/settings I should test with, besides Gen2 Gen3? Going to be about 35 min to download 😞 this speed bump to 90 Mbps can't happen soon enough with my ISP!

Just put it on max settings, 1920x1080 or higher and do a /fpsgraph 1

Also a maybe you can answer this Nodens, but why haven't I noticed this in any other games. I normally play with vsynch off and a fps cap of 65 fps on most games. Vsync doesn't seem to work correct running a mix of 2x Displayport and 1 DVI with crossfire enabled. I get bad stuttering. I am hoping the Displayport 1.2 MST hubs Accell will be releasing in the next 45-60 days will fix the vsync issue running eyefinity and trifire.

Read this to understand how vsync works, it is very accurate: http://hardforum.com/showthread.php?t=928593

EDIT: Specifically this part:

Essentially this means that with double-buffered VSync, the framerate can only be equal to a discrete set of values equal to Refresh / N where N is some positive integer. That means if you're talking about 60Hz refresh rate, the only framerates you can get are 60, 30, 20, 15, 12, 10, etc etc. You can see the big gap between 60 and 30 there. Any framerate between 60 and 30 your video card would normally put out would get dropped to 30.

This is why you see stuttering with VSync on. Game conditions that would drop your framerate to 45 will drop it to 30 instead, 19fps become 15, 14 becomes 12 and so on. Your performance is not different but due to VSync, the framerate must be locked to one of those numbers which makes the low framerate worse.

[Warboy]

Nodens wrote:
Just put it on max settings, 1920x1080 or higher and do a /fpsgraph 1



Read this to understand how vsync works, it is very accurate: http://hardforum.com/showthread.php?t=928593

I just pushed STO to max 3840x2160 max settings, with PCIe 3.0 enabled on my system and don't see anything. Is it something within Neverwinter that's triggering it? Should be the same game engine.

[Nodens]

Warboy wrote:
I just pushed STO to max 3840x2160 max settings, with PCIe 3.0 enabled on my system and don't see anything. Is it something within Neverwinter that's triggering it? Should be the same game engine.

Neverwinter uses a much improved version of the engine. STO will probably be updated to that at some point. I can not reproduce the issue on STO's version (first thing I tried before I started tweaking my engine hehe). Try Neverwinter and also tell me what cards you are using. Have in mind if it's a single card you may need to move around for a quite while for it to trigger. On SLI it starts happening usually within 5-10 minutes running around in Protector's Enclave (the basic city hub you arrive after the tutorial).

R4E3960X wrote:

AMD HD 7970 work perfectly on my system with PCI-E 3.0 x 16. 😮 with CCC 13.4 and 13.4 profile for Lora Croft extremely well

That says absolutely nothing. This needs very specific methods to diagnose.

[alyupb]

Hello,

I have tested Neverwinter on my single GTX 680, running at GEN2 speeds (no force gen3 tweak applied, however GEN3 enabled in BIOS), and can report that I do get purple spikes in the fpsgraph while running around in Protector's Enclave. The purple spikes are not constant, but they do happen at least once a minute. I'm not sure if this test is relevant to this discussion since I am not running at GEN3 speeds, but I thought I would post this anyway.

EDIT:

My specs:

Rampage IV Extreme
3930K C2 w/ Noctua NH-D14
16GB (4x4) Corsair Dominator 1600MHz 7-8-8-24
EVGA GeForce GTX 680 2GB
ASUS Xonar Essence STX
Seasonic X-1050
Intel SSD 520 240GB
2 x 150GB Velociraptor
Silverstone FT02

[R4E3960X]

AMD HD 7970 work perfectly on my system with PCI-E 3.0 x 16. 😮 with CCC 13.4 and 13.4 profile for Lora Croft extremely well.

[Nodens]

Once a minute is normal..nothing to be concerned of. GEN3 makes the graph appear full of purple spikes. All across the graph. You can try applying the tweak and see the difference:)

[Melting_Point]

Thanx Arni and Nodens, think i'll just go the cheaper option and get another 580 (when I can convince the wife that the world will end if I don't have it, that it).

[Warboy]

Melting Point wrote:
Thanx Arni and Nodens, think i'll just go the cheaper option and get another 580 (when I can convince the wife that the world will end if I don't have it, that it).

Just wait for the GTX780 or Titan LE, anything else at this point would be a waste.

[Myk_SilentShado]

Warboy wrote:
Just wait for the GTX780 or Titan LE, anything else at this point would be a waste.

And what would be the point in those purchases if you're still using an SB-E CPU? you'd still have the same problems Nodens has been discussing. A new GPU isn't going to solve anything mate, only a new CPU. I'm guessing Haswell will be fully compatible with PCIe 3...and IB-E when it comes to X79