I've seen this mentioned in a few posts around here, but never really explained (either posters weren't clear on the topic themselves, or assumed everyone else knew what the posters were talking about). That is, the relationship between system RAM and vram...that, I think I've read (or misread) the available vram is capped somehow by system RAM.

Where I'm coming from...I have a gtx590 3gb, which is 2 vid cards wrapped in one package and behaves for practical purposes like 2 cards in SLI (actually appears as two cards in all monitoring software). It has some of the hiccups that SLI brings as well. However, some people suggest that for one monitor, to run Skyrim off of only one card and disabling the other to rid the SLI bugs, and that the performance shouldn't be seen anyways. For me, this is not true - when I disable one gpu, my fps instantly drops about 35% in all places.

Further, I'm pushing this game as much as my system will allow without going crazy while still trying to maintain 50fps+ even in the worst times.
- ENB-based shaders (full AO activated in ENB)
- high shadows (but not ultra)
- 16xAF (nvidia inspector)
- 2xAA in-game, 4xMSAA & 2xSS transparency (nvidia inspector)
- 1920x1080 res (native)
- ugrids @ default
- vsync on with fps limiter@64

I have 16gb of system RAM. I disable everything on my system not needed to play the game when in-game, and give my gpu a very mild OC with Afterburner. My system RAM usage never goes beyond about 5gb while in-game (as expected I think). My cpu load can reach up to 85% for core1 in tough spots, but is pretty evenly distributed between the other cores (I use +fullproc) for the rest of the load.

What DOES surprise me a bit is that both of my gpus are, at busiest times, maxing out to full 100% usage (tells me this in Afterburner) . With 3gb of vram, everything I thought I knew about Skyrim told me this wouldn't happen. No artifacting or overheating or anything bad.

So, back to the gist of it all - some people who seem to know what they are about have referred to vram caps based on system RAM, and that Skyrim doesn't make full use of top-end vid cards. Based on what I see, neither statement makes sense...BUT I assume that perhaps:
a) I don't understand the issue (always very possible)
b.) I'm not reading my system usage info correctly (also possible)
c) my monitoring programs are lying (less likely)
d) my system behaves differently than everyone else's (extra unlikely)

Many experts around here, would love to hear some thoughts. Thanks in advance

cheers!

From what I know mate, VRAM is used constantly by AA, Resolution, and other GPU settings like shadows. Textures however, are stored in system ram, then fed to VRAM when the game requires them. Which is why when using hd texture packs, system ram usage for skyrim can be as high as 3 or 4 gig.

The only application I can think of that would use even close to 16G of RAM would be Firefox left open for a few weeks.

Adobe AfterEffects CS5 - it can use up all that RAM if I let it.

Don't forget that both GPU's mirror the same graphics data, each taking turn to display a frame.So effectively, you only have 1.5GB of vram.

They're seperate, system ram is used directly by skyrim to house its data about the contents like the AI's current jobs or say your character's current stats. Video ram is storing all the info that the video cards need to draw what's on your screen. Something to keep in mind with your GTX590 is that 3GB of memory is split between the two GPUs, so each has effectively 1.5GB to work with and effectively everything is doubled since each GPU needs a complete copy of the info to generate the frames its responsible for. Another example of that would be how each of my cards has 3GB but no the game itself doesn't now have 9GB of vram to use its only got as much as each individual card has since they're all working round-robin to draw frames. A theory on why you're seeing that vram get maxxed out but still not a direct hit could be the needed contents is still less then 1.5GB but any left over is just caching things for potential future use, no need to drop stuff out of memory until there is more room needed really.

What I'm curious about though is what is giving you that 5GB value, like what program is reporting that. I ask because a 32bit app + LAA can't see or use more then 4GB of the stuff, what I'm still foggy about is whether vram counts in that total as well.

Another thing dude, things like windows aero use VRAM also.

Until you go into a full screen 3d app, then its flushed over to that sneaky 'shared memory' (system memory mapped as quasi vram, kinda like how the swapfile is virtually mapped memory for overflow).

Mis-typed - 4GB should be. I'm getting that number from 3 different sources: windows7 performance monitor, CPUmon, and the monitoring app on the keyboard's LCD. It APPEARS like your formula is true, but "whether vram counts in that total as well" is the kind of statement that inspired this thread to begin with.



Ya, my understanding as well - though I was surprised by the extent of the fps hit when I turned one gpu off.


I have aero, and every single other windows7 piece of eye candy turned off (no desktop background, no smoothing...nothing). Pre-game load system memory usage: 1823mb.

http://en.wikipedia.org/wiki/Video_memory

Hrm, those three apps would be showing you total system memory in use rather then what specifically Skyrim itself is consuming, they wouldn't be reporting the vram usage either but gpuz or nvidia inspector do. So what I think you're seeing is win7+whatever other apps+skyrim eat about 4GB of your total system ram, the alternative that your Skyrim itself is capable of gobbling up 4GB of system memory would then raise my question: How did you find that many mods that focus on system memory and including them without bringing your system to its knees I went on a hunt a few days ago specifically looking for mods that would do that and even with my savage settings I'm still not seeing Skyrim use a little over about 1.8GB of system memory, with the settings/mods I usually play at its more like 1.6 is the usual. Oh and vram typically coasts around 2gb on a fresh load of some big area, but its easy to force upwards by doing something odd like setting that deferred shadow setting to x16.

PS: Meanwhile slightly off topic but I just tried to induce a full 3GB vram consumed setup and decided to give all three of the shadow resolutions 8192 (typically I keep them at 4096). Well yah the vram went up about 200MB...but my FPS went up as well. I don't get it, I really don't get this game's shadow engine *at all*

Ofcourse yea, lol .

oh yes those system ram numbers I gave don't isolate Skyrim...its always been Skyrim + Windows + crap.

As for the mods, I use the full STEP program + Skyrim Enhanced Shaders (ENB-based full AO)...I dialed-down the SkyrimHD mod to lessor setting because I needed extra smoothness for vids (and the 4K textures weren't adding anything on youtube). So, if I read you right...1.8gb for my windows+crap...then ~2.2 for my modded Skyrim = ~4gb system ram...but you were unable to get your modded game beyond about 1.8 for skyrim alone? Keep in mind the STEP suite of mods is massive, and ENB likely does more than just add to vram (?). As for why my system isn't on its knees, does that mean any overflow load is going to gpu (on top of normal gpu tasks)? It would explain why when I turn off SLI, I take a ~25fps hit right off the top. Because really, ONE gpu @ 1.5gb vram should be enough...but I think more is going on here. I dunno...I feel kindof dumb right now LOL

Step like this step? http://www.skyrimnexus.com/downloads/file.php?id=11 The file is 7MB, can't really see it devouring system memory that savagely Tytanis for instance is 131MB at this point and that's one of about a dozen texture pack type mods I've got loaded.

Aye so that shows you how you're reading ~4gb memory used since yah that'd be counting everything in system memory, btw no worries that just means you have a lot of head room since skyrim itself is allowed to use up to 4gb for itself. I just use regular old task manager to watch the tesv.exe and it'll tell you specifically how much its eating and then gpuz to watch my video cards. But yah I haven't managed to push beyond 1.8 system ram consumed and that was when I was playing around with the 13 & 15ugrid settings, apart from that I've got quite the laundry list of mods going too. There was another thread talking about system memory and some people were posting screens of process monitor showing their tesv.exe consuming north of 2.4gb so I really dunno where they're finding those mods but that's just ridiculous to consider since without any mods and stock ultra settings I was barely going over 1.2gb back in the day. But yah SLI is good, using just one GPU I'd be forced to scale back my settings *alot*, my mantra has been if most scenes display at north of 50fps then I haven't found enough stuff for the video cards to be chewing on and went looking for more mods to pile on Your GPUs are purely devoted to drawing what's on your screen and it sounds like you've got a good mixture of mods/performance so just keep going on that path for sure, certainly better then the stock setup where for instance even with stock ultra and the dragon-reach -> tree view my GPUs were at 17% each.

Yes that STEP link, but that 7MB file is only the pdf guide + compiler's own shaders...no, the STEP mods are the mods he recommends...these total about 3.6gb in hdd space (mostly texture mods).

btw - that tree view is often my fps bench test location too...in-game furmark

Ahhhh, well then sounds like something I should down load and take a look at for sure.

Here's why VRAM and system RAM are "linked"

Skyrim, like most software right now is 32 bit. This is proven with the need for the LAA patch, which allows a 32 bit program to address up to 4GB memory. Without LAA, 32 bit apps can only address 2 GB memory.

This address space limitation is on the combined total of Video memory and System memory.
Before patch 1.3.10, you might see 1.2GB of RAM allocated to Skyrim, but it would be out of space because it was using 7xx MB of video RAM too, meaning close to 2GB total.
After that patch, there is room to breathe.

Before the patch some people would exceed 2 GB and this was the cause of some crashes. Adding LAA allows that limit to be bumped to 4GB and this solves some crashes and also allows people to experiment with larger textures and such.

Also, as another poster mentioned, the video card will use system memory if it needs it for textures, and there is some link there. However, I think most of the reason people would be hearing about this is due to the combined addressable memory limit of 32 bit apps. It doesn't matter how much system memory you have, you could have 128 GB of memory, but Skyrim cannot use more than 4 GB now that it's LAA, and couldn't use more than 2GB when it was not Large Address Aware.