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

Nodens
Level 16
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.
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RealBench Developer.
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Arne_Saknussemm
Level 40
Hmmm thanks Nodens! Interesting stuff! Can I just ask why you suspect SB-E in general and not your CPU for this? Any way I could test this apart from buying Neverwinter...?

I just said goodbye to my 680s.....will this be the same with 690s and Titans?

Arne Saknussemm wrote:
Hmmm thanks Nodens! Interesting stuff! Can I just ask why you suspect SB-E in general and not your CPU for this? Any way I could test this apart from buying Neverwinter...?


Because it appears that the signaling issues are constant, I checked eight CPU samples and all I saw was variation in frequency of the driver stalling between samples. I'm fairly certain that no SB-E CPU can actually operate without the driver stalling. I believe the only difference is in how often which determines how sever it is. But anyhow it should hurt stability and performance as long as things wait for the driver to recover.. BTW Neverwinter is free to play, just download it, make an account and check it. It's the only easy test I currently know..do a /fpsgraph 1 and check for purple spikes in the graph.


I just said goodbye to my 680s.....will this be the same with 690s and Titans?

There should be no difference with the 690..as for Titans I don't know..they are newer perhaps they account for this..
RAMPAGE Windows 8/7 UEFI Installation Guide - Patched OROM for TRIM in RAID - Patched UEFI GOP Updater Tool - ASUS OEM License Restorer
There are 10 types of people in the world. Those who understand binary and those who don't!

RealBench Developer.

Nodens wrote:
I checked eight CPU samples and all I saw was variation in frequency of the driver stalling between samples


Yeah, good stuff....OK, that's something to investigate....but gen 2.0 it is, until Intel actually gives the top of the line CPUs Gen 3.0 capability. :rolleyes:

http://www.expreview.com/topic/img/review/News/201304/0425/1007b.png
http://www.expreview.com/25087.html
too bad Ivy ridge isnt much better than sandy I don't think it justifies an upgrade from a 3930k.
Besides I am more focused on the 780s coming out may 23rd.
http://www.expreview.com/25247.html
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cx-ray
Level 12
I was thinking along the same lines after seeing weird slowdowns in Crysis 3. I was planning to perform some further tests after I've put my rig back together.

maximiza
Level 11
Could that be do to intel speedstep? I noticed pauses and freezes with it enabled

alex_123_fra
Level 7
I noticed the same behaviour with my system and Gen 3 when benching. Frame rates were incredibly spiky with many troughs. I assumed it was an issue with my system only. Gen 2 is perfectly smooth and stable.
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maximiza wrote:
Could that be do to intel speedstep? I noticed pauses and freezes with it enabled


EIST has always been disabled on this machine along with C-States but EIST causes that due to DPC latency penalties it incurs. This is different.

alex_123_fra wrote:
I noticed the same behaviour with my system and Gen 3 when benching. Frame rates were incredibly spiky with many troughs. I assumed it was an issue with my system only. Gen 2 is perfectly smooth and stable.


Nope it's not just your system. The driver "stalls" while waiting for the card. The only question is how "often" it happens on everyone's system. For yours to be apparent with benching, the issue must be in a very severe form.
RAMPAGE Windows 8/7 UEFI Installation Guide - Patched OROM for TRIM in RAID - Patched UEFI GOP Updater Tool - ASUS OEM License Restorer
There are 10 types of people in the world. Those who understand binary and those who don't!

RealBench Developer.

What revision Chip are you using? C1's are notorious for showing bugs......

If you have C1 Intel has a program for you to get the C2 version.

Email me and I can help you out

machivell@gmail.com


They send this blanket messege out to cover not supporting Intel's #$%^ up on the SB-E's instruction or lack on proper instruction placement.

"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 KNOW YOU HAVE THE C2 version don't worry!!!! They are protecting their asses from a support nightmare hehehe


Some will say that the diff between C1 and C2 is just the VT-d which is the virtualization piece it's also the PCE 2 vs. 3 issues as well. I've tested both in the lab!!!!!!!!!!!!!! Below is the link explaining their F-up. If you have C1 goto the correct link and have them FIX it ASAP!



http://www.techpowerup.com/forums/showthread.php?t=156625

LOOKING OUT FOR YOU!

Machivell










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