Teaser of GTX460 1GB vs 2GB SLI Surround Review

[Paradigm Shifter]

Wotcher folks, been some time since I was really active. Anyway, just thought I'd post a teaser of some results I've got for Need for Speed: Shift in nVidia Surround on 1GB and 2GB GTX460s...

While obviously the extra VRAM makes bog all difference at 1920x1200, even with 4xAA on, it makes huge differences at Surround resolutions...





Without looking at the filenames, can you tell which SLI setup is which? ;)

[JohnnyWakko]

Hey Paradigm

Good to see yer, & thanks for the info...can you label those graphs please, I'm finding it hard to figure out which SLi setup is which.

EDIT: I just read the file names.

[ratfusion]

Well that's a pretty stark difference. Can't wait to see the rest. I hope you get the opportunity to throw in a 5040x1050 on one of the tests to see which side of the nosedive point its on.

[thales100]

Very nice, thanks for this comparison ! :cheers

[Paradigm Shifter]

The nosedives happen exactly when I expected they would - when the GPU runs out of VRAM and starts swapping to the system RAM. Basically, as long as the game in question doesn't use more than ~900MB of VRAM for a given res and details settings, it's fine. As soon as the VRAM usage goes over ~980MB, framerate tanks.

It's also interesting that some games, if they can't fit textures in the VRAM, appear to preferentially use system RAM instead.

This actually calls into question the performance conclusions of just about every modern GPU review... "oh, this card can't handle game x at these settings and res, it's not powerful enough" is far more likely to be "this game runs out of VRAM and chokes at these settings. More VRAM would help a lot!" This is particulary noticeable in Need for Speed Shift and Burnout Paradise... I can get 6064x1200 running with 8xAA on a 2GB card, but it chokes and splutters with 2xAA on a 1GB.

I've got that data too, but lots more crunching needed. Mostly of my work data that still ain't done! :(

This actually makes me want to see what tri-SLI GTX480's could do if they were given 3GB of VRAM apiece. Because there were lots of scenarios in my GTX460 testing where VRAM usage would exceed 1.5GB... and still be pretty much playable on the "underpowered" GTX460. Of course, there were also several occasions when the 460 just wasn't a powerful enough GPU to push all the pixels... ;)

[Paradigm Shifter]

ratfusion, sorry, for some reason I can't persuade 5040x1050 to work with my Surround setup. I'm guessing it's a driver bug.

[Gilly]

Those GTX460's are little monsters :P

[Paradigm Shifter]

They are.

I've given the review to Ibrin, so it's going in the wiki. I'm not really up on the wiki so I dunno when it'll be available in that respect.

[scheffchen]

Dear Paradigm Shifter, dear forum members
I watched your charts with much interest and sorrow at the same time.
For Flight Sims I am planning to upgrade my rig to nvidia surround with the following specs:
- Second GTX470 zotac amp edition
- 3 new U2711 by dell (each with 2560 x 1440 resolution).

Since the vRAM seems to be a big issue when dealing with such high resolutions. Do you think that a third gtx470 will do the job, or does every card need to have a huge vram (like 2GB or even more)?
because the u2711 does have an incredible resolution at that size, I thought that AA might be pointless from now on.

I was already in the ordering process at my favourite website until i stepped over your post. Maybe you could share your advice and thoughts.
my actual system is a i7 930 @3.9ghz, 6gb ram, gtx 470 zotac amp edition

Greetings from Germany :)
Boris

[Tamlin]

Unfortunately, if the problem is a memory limit, adding an extra card will only give you more processing power, while the memory limit will still be a bottleneck when using AA. :(
If you wonder if AA is required on such high resolution as with the Dells, I suggest you try it out first with the screens and then order cards. The use of AA and how much is needed is very user dependent. :)

[Paradigm Shifter]

This is a nasty problem, actually.

The GTX460 is the only Fermi based card that really has enough VRAM to cope with the demands of AA enabled Surround, but it's not as powerful as a GTX470 or 480 in terms of raw processing power.

This results in a tradeoff - more VRAM, or more grunt?

Honestly, I'd try running those panels with AA off, and see how it goes. If it really, really needs it... try dropping the res.

The only card I know of that actually does everything I want right now in terms of Surround (lots of VRAM, more power than a 460) is a Quadro card that is basically a cross between a 470 and 480 (470 shader count, 480 memory bus) paired with 6GB!!! of GDDR5. It comes with a nasty price tag of £4200, too. So isn't really a feasible proposition. ;)

I realise this probably won't help you much - if you were going to game at 5760x1200 or such, I'd say go dual 2GB GTX460s. As you've got 7680x1440 to push instead, I don't think you can afford to lose the extra power of the GTX470s. :(

[ratfusion]

scheffchen,

Check out the benchmarks in this review: http://www.hardocp.com/article/2010/08/16/sli_cfx_pcie_bandwidth_perf_x16x16_vs_x16x8.

Among the benchmarks, they're testing at 3x 1920x1200 resolution a 5870 at 1gb and 2gb of ram, with very little difference realized. It could be a 5870 limitation, or it could be the different cross-section of games they tested weren't as demanding on vram. All of their testing focuses on keeping the framerate playable though, they may not be cranking things up enough to tax the memory.

Paradigm has found at least one game that can demand enough vram to reaaaaallly clearly make a difference, though. There is more to be learned here.

Paradigm, if your full review is now posted I haven't been able to find it, a link would be greatly appreciated.

[scheffchen]

Hello and good morning everybody,

first thank you for the quick answers so far.

I agree that the power of a gtx470 in comparison to the 460 can be critical.
The charts showed, that with the 1gb cards there was a short drop in frame rate to 9fps. When speaking about the flight sims (FSX, Lock on 2, Black Shark) these use older engines that rely more on processor power than on high-res textures. Conclusion may be, that for actual games with Hires graphics, I may have to lower the resolution while on the sims it could work out.

Ratfusion, thanks for the link to that review, it seems like the performance is very game dependant which underlines my thesis.

Maybe next year there will be GFX-cards available with a vram of >2gb for a reasonable price.
I still have to think whether to buy the monitors or not but I tend to to so.

Regards
Boris

[Paradigm Shifter]

As HardOCP uses "best playable settings" the results I obtained can't really be directly compared - I was after trying out a distinct set of perhaps-over-the-top settings at Surround resolutions and seeing whether it made cards choke.

I expect I could probably make GTX480 SLI choke with some of the settings used, never mind the mind-range cards. ;)

There are graphics cards with 2GB of VRAM available for a reasonable price... they're the GTX460. :D I just think that Metro 2033 in particular is going to be utterly unplayable with the details turned up, even on 2GB cards, because of the sheer power needed for that game.

[Gilly]

some more info here:

http://www.hardocp.com/article/2010/08/17/geforce_gtx_460_sli_vs_radeon_hd_5870_cfx_5760

Benches 2x gtx460 against 2x hd5870. And mentions a little about AA and the 1GB Frame buffer.

[fuzioninfinity]

Thanks for posting this up Paradigm. I really had no idea how much of an impact VRAM had on performance in surround until I saw this. It does raise one question however, you mention that after a card maxes out it's VRAM it goes to normal RAM, would acquiring more RAM help increase framerates when this occurs in games, or is it the offloading of the VRAM to the RAM itself what causes the massive framerate drops? If so, would it also be possible to perhaps dedicate an amount of RAM to VRAM, permanently - to avoid the system crapping out when it has to offload to RAM?

I ask this because I had a rather odd issue awhile back that I never sorted out.. I had purchased a new processor (went from a dual core to a quad core), and upon booting up I lost about 750mb RAM. In BIOS it recognized all 4 Gigs of RAM, but only 3.25GB we're "Usable". I checked for bent pins, dust, re-seating ram, updated bios, troubleshooted for days, never figured out the problem. All my games still worked fine, no blue screens, so I ended up going on my way, decided to quit before I just made things worse. I went to update my windows experience index and when I did I found that windows was indicating my Video Card had almost 2.5gb of VRAM, accounting for my mysteriously lost RAM. This problem went away when I got a new motherboard, and I haven't been able to replicate it, not that I tried. Odd that I'm finding myself now trying to replicate this problem that drove me mad :P.

Sorry if I'm mucking up your thread here with my silly questions >_> Just curious about the wonderful inner-workings of VRAM/System RAM.

[Gilly]

you need a 64 bit OS to address more than ~3.25GB system ram

[fuzioninfinity]

I was running Windows 7 Ultimate 64-bit at the time, and I still am; if it matters. :P I'm well aware of all of that. I had full use of my 4GB RAM before I installed the new processor. But that wasn't really the point of my little anecdote, the problem went away with my new motherboard (perhaps a damaged, mobo? I dunno; Still using the same RAM.)

[Paradigm Shifter]

Right, I'll try to answer all your questions, but in a random sort of way...

The reason you had RAM vanish when you swapped cards was it was probably borrowing system RAM for the GPU ("Hypermemory" was what ATi called it, "TurboCache" nVidia).

Acquiring more system RAM might help to some extent. Bear in mind that system RAM has, what, 6-8GB/s of bandwidth available? Most of the high-end video cards are looking at 100GB/s and upwards. Big, big difference there. Also, when running in SLI, I suspect it chews up double the system RAM expected (it needs to mirror data for each GPU, yes?) so unless you were thinking of popping in, say, 12GB... I think the change would be minimal. Also, it would still go swap to pagefile (even slower than system RAM, from 6GB/s to 150MB/s max...) which is what I think Aliens vs. Predator was doing for me when testing at the really ultra settings.

Dedicating system RAM to VRAM is just a waste of time IMO. It's so slow that it's not worth it. The use of system RAM as VRAM by integrated chipsets is one of the reasons why they suck, after all.

You got PM.

[ratfusion]

Paradigm did your full review ever get posted? I can't seem to find it.