Topic Title: Skyrim and Crossfire - frame pacing issue?
Topic Summary: Strange issues with Skyrim using Crossfire and frame pacing?
Created On: 06/19/2014 06:19 PM
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 06/19/2014 06:19 PM
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SomeRandomUser
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After doing quite a bit of searching around the internet for the last week or so, I've found that Skyrim and Crossfire have a long and storied past.  It appeared the early issues (late 2011, early 2012) were fixed long ago.  After that ENBs became popular along with the ENB depth-of-field effect, which caused new problems.  The answer there was typically to disable DoF when using Crossfire.  However, I haven't seen many posts on the subject of Skyrim and Crossfire in about a year, so I want to post here with a possibly new issue to see if anyone else has experienced it.

I originally played Skyrim on the PS3, but have recently been replaying it on the PC due to the wealth of amazing mods.  Due to the pretty heavy GPU requirements of a heavily modded Skyrim (especially when running an ENB), I picked up a second 7950 gpu on Ebay to run in Crossfire mode.  That's where my troubles have started.

Pertinent specs:

 

  • 2x Sapphire 7950 gpus (same model and firmware)
  • Catalyst 14.4
  • Corsair HX750 psu
  • 8 gigs of ram
  • Intel DZ77BH55K mobo
  • I5-3570K cpu
  • Windows 7 (64-bit)
  • no overclocks

Symptoms:

In certain outdoor areas of the game (mostly cities and areas with lots of trees?), everything will start out fine and perform great, but after a few seconds (5, 10, 30, sometimes 60 seconds) the framerate will suddenly begin to drop down to a crawl for no apparent reason.  It will get worse and worse, almost to the point of stopping, and then the weird stuff happens.  Shadows will suddenly grow and start to turn huge areas of the game black.  It's a very strange effect and a bit hard to describe.  When this first starts happening, I can stop it by very quickly hitting Escape and exiting the game cleanly.  If I wait long enough and let it happen, though, the game will eventually freeze up, requiring me to either kill it, or reboot my entire machine.  It's not entirely consistent as to where the problem occurs.  If I fast travel to Riverwood, for example, sometimes the problem will start almost immediately (as soon as the area is done loading), and other times I can run around briefly before it starts.  So *something* seems to trigger it, but I can't seem to determine what.

I have tried removing all my mods and reinstalling Skyrim (no small feat when you're dealing with 100+ mods), so it was a clean, fresh install.  Same problem occurs, but an unmodded Skyrim takes longer to get the issue to happen.  Lots of mods and an ENB tend to allow me to reproduce the problem very quickly.  It happens either way, though.

If I disable Crossfire, Skyrim runs fine, modded or unmodded.

I should note that all other games and stress tests I've tried work fine in Crossfire mode.  For example, I'm able to run Unigine Valley and Heaven for 30 minutes straight with no problems.

The last thing I tried last night before giving up for the night was to disable frame pacing in the CCC.  After I did that, I was able to run around in Skyrim for a good 5 minutes with no issues.  (Other than the framerate stuttering that is common without pacing enabled.)  It was only a 5 minute test, which isn't really conclusive, but it's a good start.  I hadn't yet been able to play for 5 minutes without an issue, so this is a positive change!

UPDATE:  I'm almost certain the issue is with the frame pacing feature.  I disabled frame pacing again, but this time I played the game for an entire hour with no issues.  I then enabled frame pacing and tried playing the game again.  That immediately started having the same problems listed above.

Without frame pacing I do indeed get some pretty bad occasional stuttering, but at least it's stable.  In most areas I get 50-60 fps (vsync capped at 60), and as I walk along it will suddenly stutter pretty badly for a half a second, then pop right back to a smooth 50-60 fps.  Interestingly, with Crossfire disabled those brief moments of severe stuttering don't occur at all.  I get a much lower frame rate, of course, but it's a consistent low frame rate.



Edited: 06/20/2014 at 04:12 AM by SomeRandomUser
 06/19/2014 07:00 PM
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backFireX64
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Just tried skyrim legendary edition in crossfirex.

No problems, scaling good, temps normal, frame pacing off

All settings ultra, 4x AA, 1080p, v-sync on.



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 06/19/2014 07:24 PM
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SomeRandomUser
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Good to know.  Can you try it with frame pacing on, possibly?  And any chance you have any mods? I'm suspecting this might be somehow be related to shadows. I'm finding that the more shadows an area has,the more quickly the problem occurs. In particular, you can enable the treesreceiveshadows option to increase shadow load...

 06/19/2014 07:34 PM
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backFireX64
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Frame pacing=on, same normal results.

 

You mean the "bTreesReceiveShadows=1" ?

 

I don't use mods.



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 06/19/2014 07:38 PM
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SomeRandomUser
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Originally posted by: backFireX64 Frame pacing=on, same normal results.

 

You mean the "bTreesReceiveShadows=1" ?

 

Correct.  I'm only guessing at the issue, though, based on what I've noticed through my own testing thus far.  It *seems* that areas with more shadows have an issue more quickly.  In the case of folks running an ENB mod, there are quite a few shadow options that get turned up, such as:

  • bTreesReceiveShadows=1
  • bDrawLandShadows=1
And so forth.  With an unmoddified game, even with Ultra settings, those are all turned off, I believe.

 06/19/2014 07:43 PM
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backFireX64
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I'm not sure .......

 

I just installed the game but i might have a modified .ini file from an earlier time. Don't remember.

 

Can you, by any chance, recommend to me some good visual mods that my HD6990 can handle ?



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 06/19/2014 09:16 PM
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SomeRandomUser
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You bet.  A 6990 is still a pretty nice card.  When it comes to Skyrim mods, how much time you want to invest will determine how deep down that rabbit hole you want to go.    Have done any Skyrim modding before, or would this be your first time?

The fastest (but probably least impressive) graphical upgrade you can do if you are using Steam is to install Skyrim's high resolution texture pack DLC.  It's free, and it's a great place to start as Steam just installs it for you and you never have to think about it again.  Plus, it's an official texture pack from Bethesda, so there's no mucking about with compatibility, configuration, and all that.  The texture resolutions are only a *little* bit upgraded, though, so it's not a huge change.  But it's free, so hey.

If you really want to blow your mind with some of the best game graphics you've ever seen (yes, even with an old game like Skyrim), you move beyond just that texture pack DLC and you start moving into the world of 3rd party mods and especially ENB mods.  (No one really knows what ENB stands for.)  Most mods upgrade the textures and models in the game, making everything just look better, have higher polygon counts, etc.  That's the most basic kind of mod.  The ENB engine, though, modifies the existing rendering engine in Skyrim with a custom engine that increases the quality of almost every aspect of the game's rendering engine, including lighting, shadows, effects, etc.

With my first venture into serious Skyrim modding I started with "Realvision ENB," since the creator lays out all of the mods he recommends, along with his own ENB configuration:

http://www.nexusmods.com/skyrim/mods/30936/?

That one is nice because it takes a lot of the guesswork out of figuring out which mods you want.  Basically, steps 1-3 are all you need.  Keep in mind it's still a good amount of work getting all that downloaded and installed if you've never done Skyrim mods before.  You'd first want to install the Nexus Mod Manager to let you manage all those mods.

If you want the quick and dirty upgrade just to see what it's all about, do this:

  1. Install the texture pack DLC from Steam.
  2. Go to the Realvision page and do steps 2 and 3.  I would go with option B in step 2, as I feel the "Enhanced Lights and FX" mod (ELFX) is much better than "Realistic Lighting Overhaul" (RLO).
If you'd like further help, feel free to ask.  The Skyrim mods rabbit hole is *deep*, so there's almost no limit to how far you can take it.

 06/19/2014 09:33 PM
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backFireX64
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Yep, these will do fine.

 

I already have the 3 high res.text. packs (.esp files), but i don't have the game on steam, if you know what i mean ....... but that will be easier for me to install some mods.

To answer you about modding experience, i will ask this:

Do you know how difficult and time-consuming is to install different unofficial patches/ mods for a simple game like pro evo soccer (there are tons of them and i've tried them all) ? I'm sure you can imagine.

But if i managed to enhance crysis 2 with some of the best mods (maldo HD 4.0 - Blackfire mod), i think i can eventually handle skyrim.

 

Thank you for a most valuable help. I'll try your suggestions when i have some spare time.

Keep in touch on this forum.

Thanks.



-------------------------

gigabyte X58A-UD3R rev.2, core i7 975 3.9ghz (stock voltage), windows 8.1 64-bit, corsair 12gb DDR3 1600mhz 7-7-7-20 RAM, xfx HD 5970 + gigabyte HD 5970 (stock clocks), coolermaster ultimate 900w PSU.
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 06/19/2014 09:50 PM
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SomeRandomUser
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Good deal.  It's also important to note that even though your 6990 has 4 gigs of ram, it's actually 2 gigs per GPU just as it would be with two separate cards.  When running in Crossfire, each gpu's dedicated memory is a duplicate of the other, so your card has an *effective* 2 gigs.  I apologize if you're already aware of that, but I wanted to mention it.

That being the case, if you start installing lots of high resolution texture map packs, you may want to choose the "lite" or "1k" versions on most of them.  The fantastic "Skyrim HD" pack, for example, has both a "lite" and a "full" version.  You should pick the lite version.  It's still much higher res than even the DLC.  I use the Full version (along with many other texture maps kits) and on my 7950s (which have 3 gigs) they consume 2.7 to 2.8 gigs.  Running it pretty close. 

 06/19/2014 10:16 PM
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backFireX64
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Yea, my next card will have min. 4 gb vram on single gpu.

A 6-8 gb vram on a single gpu would be ideal and future-proof, since most multi-platform games will be probably built with the 8gb unified memory of the ps4 in mind.

First example being watch_dogs.

 

Am i wrong ?



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 06/20/2014 01:09 AM
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SomeRandomUser
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Originally posted by: backFireX64  A 6-8 gb vram on a single gpu would be ideal and future-proof, since most multi-platform games will be probably built with the 8gb unified memory of the ps4 in mind.

 

 

That "unified" memory on the PS4 means it is shared between the gpu and the application data, so not only do the texture maps and other graphical assets have to fit in there, but the entire application has to fit in there.  So while a shared 8 gigs is definitely a whole lot more than previous consoles, it's a bit more on par with modern computers when you consider that a modern computer has 4-8 gigs of ram for applications and 2-4 gigs for the gpu.  So likely, upgrading your computer to a gpu with 4 gigs will probably cover you for a long time.

 06/20/2014 04:03 AM
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SomeRandomUser
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UPDATE:  I'm almost certain the issue is with the frame pacing feature.  I disabled frame pacing again, but this time I played the game for an entire hour with no issues.  I then enabled frame pacing and tried playing the game again.  That immediately started having the same problems listed above.

Without frame pacing I do indeed get some pretty bad occasional stuttering, but at least it's stable.  In most areas I get 50-60 fps (vsync capped at 60), and as I walk along it will suddenly stutter pretty badly for a half a second, then pop right back to a smooth 50-60 fps.  Interestingly, with Crossfire disabled those brief moments of severe stuttering don't occur at all.  I get a much lower frame rate, of course, but it's a consistent low frame rate.



Edited: 06/20/2014 at 04:11 AM by SomeRandomUser
 06/20/2014 06:18 AM
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HoneyBadger84
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Skytim has had issues with Crossfire since release and some of them which are game-side bugs were never really resolved.  If you can get away with running it with crossfire disabled,  I say save the power draw and do that.

The pacing feature was designed for games with micro stutter issues, Skyrim wasn't really one of them, but it is quite odd that it causes issues like this for you.

Have you tried swapping card positions and seeing if on the newer card with crossfire disabled you get the symptoms? 



-------------------------

CPU: i7 3930k @ 4.6GHz 1.29V (Corsair H110-cooled) ~ Motherboard: Asus RoG Rampage IV Extreme 
RAM: G.Skill Sniper Gaming Series (4x4GB 2133MHz, CL9) ~ PSU: Corsair AX 1200W ~ Case: Enermax Fulmo GT
GPUs: 3x HIS R9 290X Reference (Core) Editions in TriFire, Max Load Temps: 71C/70C/71C during OC testing :-P

 06/20/2014 08:20 AM
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backFireX64
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Originally posted by: SomeRandomUser UPDATE:  I'm almost certain the issue is with the frame pacing feature.  I disabled frame pacing again, but this time I played the game for an entire hour with no issues.  I then enabled frame pacing and tried playing the game again.  That immediately started having the same problems listed above.

 

Without frame pacing I do indeed get some pretty bad occasional stuttering, but at least it's stable.  In most areas I get 50-60 fps (vsync capped at 60), and as I walk along it will suddenly stutter pretty badly for a half a second, then pop right back to a smooth 50-60 fps.  Interestingly, with Crossfire disabled those brief moments of severe stuttering don't occur at all.  I get a much lower frame rate, of course, but it's a consistent low frame rate.

 

 

I have never seen a game of mine benefit from frame pacing, but that may be because i use an HD6000 series card. So i have turned that feature off in global settings, because it actually lowers my in-game fps.

I think it was implemented with the HD7000 series card and so forth in mind.

A dx triple buffering setting or a dynamic framerate limit can have similar or better results than frame pacing, just as it has with nvidia.

 

Skytim has had issues with Crossfire since release and some of them which are game-side bugs were never really resolved.  If you can get away with running it with crossfire disabled,  I say save the power draw and do that.

 

Yes, you are right.

I remember having those issues myself and ended up doing what you suggested. Not much of a performance hit anyway.

But a full modded Skyrim will be difficult to run with a single HD7950.....

 

SomeRandomUser:   did you create a new .ini file ? Maybe a wrong config. is giving you trouble. I would try previous whql drivers (or even beta) as well, if i were you.



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gigabyte X58A-UD3R rev.2, core i7 975 3.9ghz (stock voltage), windows 8.1 64-bit, corsair 12gb DDR3 1600mhz 7-7-7-20 RAM, xfx HD 5970 + gigabyte HD 5970 (stock clocks), coolermaster ultimate 900w PSU.
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 06/20/2014 07:10 PM
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SomeRandomUser
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Originally posted by: HoneyBadger84

 

Have you tried swapping card positions and seeing if on the newer card with crossfire disabled you get the symptoms? 

 

 

I have not tried using *only* the new card.  I have considered it, but since every other game and benchmark runs great in Crossfire mode, I sort of ruled out the idea of the new card having some sort of a problem.  Wouldn't be a bad idea to test, though.

As far as simply running Skyrim in single-GPU mode, I can certainly do that (and have been for a long time prior to recently purchasing the second gpu).  As backFireX64 said, though, the real issue is when you start modding Skyrim, *especially* when you use an ENB.  The GPU load at that point gets significant enough that the frame rates on my 7950 drop into the high 20s in particularly complex scenes.  With dual 7950s, though, those same scenes will run in the 50s,which is fantastic.

One thing I have not tried yet is frame rate limiting rather than vsync.  The ENB engine supports that, so maybe I'll try disabling vsync and enabling the fps limiter (at both 30 and 60 fps) to see how it performs *without* Crossfire frame pacing enabled.  Then maybe I'll also try enabling frame pacing after that to see what happens.

To reiterate, with frame pacing disabled the game *does* work great, it just has occasional (but very noticable) stutters that do not occur in single-gpu mode.  So I'm perfectly fine playing the game as-is (Crossfire without frame pacing), but I also don't mind a little bit more experimentation to see if I can nail down a stutter-free experience.

 06/20/2014 07:23 PM
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backFireX64
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When it comes to stuttering, a framerate limit or a framerate lock to screen's refresh rate can help tremendously.

 

I couldn't enjoy far cry 3 without it.

But i guess it depends on the drivers as well.



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 06/20/2014 08:11 PM
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SomeRandomUser
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Originally posted by: backFireX64 When it comes to stuttering, a framerate limit or a framerate lock to screen's refresh rate can help tremendously.

Good to know.  I'm new to the idea of a frame rate limiter in a game.  I'm very familiar with vsync and how it works, but these limiters are new to me.  Are they still back (double) buffering frames like vsync, but releasing frames at an even lower speed?  Or do they operate in some entirely different manner?  I think I've read that fps limiters don't cause the input lag like vsync does, so I'm guessing they are not back buffering any frames like vsync does.

 06/20/2014 09:24 PM
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backFireX64
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Well, unless you are one of the million people who play Crap of Dully (typos intended) with a 10.000 dpi mouse over a smooth, battery- working ice-cooled micro-fiber surface, on a 120 hz - 0,000000000001 ms latency monitor, you are likely to not notice any lag.

 

Taken from @Exitios/ GeForce Forum:

 

" Modern graphics cards, by default, operate using a technique called double buffering. The video card will store the frame currently being displayed into buffer A while it draws the next frame in buffer B. When the back buffer (B) completes its frame, the display buffer (A) will be purged and then the completed frame will be flipped over to be outputted to the monitor. Triple buffering forces the card to create a third buffer, in effect using an additional 50% of the available memory for frame storage. The display buffer will store and transmit completed frames as per usual, but instead of the GPU only being able to write to one back buffer, it can now write into two, which will be copied to the display buffer according to the frame queue. This technique can prove to be useful when the frame rate falls below the refresh rate of the monitor, a critical point when the GPUs can begin to complete their work before or just after the monitor has refreshed. Consequently, with double buffering, this will cause both buffers to be filled and the GPU is forced to wait before completing the succeeding frame; with the addition of another back buffer, the GPU can continue to render frames without being locked out. Triple buffering can only be forced when vertical synchronization (covered below) is active; this is to reduce the chance of frame shearing. Triple buffering can reduce performance because of the increased memory consumption, and will offer no benefit if the frame output rate is higher than the refresh rate of the monitor. Additionally, triple buffering can introduce slightly higher input latencies because of prolonged storage times. "



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 06/20/2014 09:35 PM
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SomeRandomUser
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Originally posted by: backFireX64 Well, unless you are one of the million people who play Crap of Dully (typos intended) with a 10.000 dpi mouse over a smooth, battery- working ice-cooled micro-fiber surface, on a 120 hz - 0,000000000001 ms latency monitor, you are likely to not notice any lag.

 

 

I definitely do not notice input lag.    I've never been a fan of first-person shooters or other games that require extremely precise, accurate mouse inputs.  I prefer RPGs and adventure games, so I always like to use vsync as long as it doesn't hurt the frame rate too badly.

I was mostly just curious how frame rate limiters worked compared to vsync.  I'm assumimg they are just using some sort of timer, and never rendering faster than 1 per whatever time interval you configure.  So at 60 fps, you are rendering a frame every 16 milliseconds.  If the frame limiter detects that is just completed a frame in 10 milliseconds, I'm guessing it just waits another 6 milliseconds before it renders the next frame?  Or something along those lines?



Edited: 06/20/2014 at 09:51 PM by SomeRandomUser
 06/20/2014 09:44 PM
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backFireX64
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Haven't the slightest idea mate.

 

I usually test my options and stick with the one that works, maybe learn something along the way.

I'm usually too lazy to go into details.

 

But now, look what you have done.

It has now become a point of interest to me.

You're gonna make me study, aren't you ?

(he he)



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