Great SLI or Crossfire performance wanted

michaeljhuman

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I bought two Sapphire Radeon 6950 OC edition cards.

It works very nicely BUT I am dissapointed with Dirt 3. I am not sure why, but I only get 80 fps on max settings. Of course that's more than sufficient for smooth performance - BUT I had higher aspirations when I built this PC. It's the first PC I have built in a long time which I intended as a very high performance gaming PC (you know how it is sometimes, you just want something you can be proud of.)

So I am thinking of spending yet more money so I can smile when I run all these benchmarks.

What it looks like to me, is that dual GTX 670 cards, might be the best deal going. It's $800, but it sure looks like it's hard to step up a lot from what I have for less.

Dual 7950s might be an option as I can chop up to $100 off that $800. But the GTX 670 seems superior and perhaps worth the $100.

Not sure, but the lesser cards, such as the 7850 don't seem great when compared to the 6950?


 

kevin83

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Stepping up to gtx 670s would certainly be the way to go in my opinion. Would you mind telling us the rest of your system's specs? Dirt 3 is a cpu-bound game from what I've heard so changing your graphics cards probably will not even effect that game at all.
 

schnitter

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For $800 why not just get the 690 GTX which is ONE dual card that will generate less heat. I don't understand people who buy two video cards day 1. SLI/Crossfire scaling isnt "double the performance" but you sure are paying double the price. I find it always best to buy the best card you can afford and SLI/Crossfire down the road. Less heat, less noise, more performance!

EDIT: And as above poster said, perhaps it is your CPU or something else bottlenecking your system. Does your MoBo support PCI E 3.0 or is it "just" 2.0? Upgrading to a GTX 690 and having an AMD Processor wont do jack.
 

kevin83

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If you're going to quad SLI, I can see how the gtx 690 makes sense. If you aren't, I'd rather save the $200 and get 2 gtx 670s for very similar performance numbers. I've never seen a gtx 690 sell near $800, it's always been around a grand on newegg.
 

michaeljhuman

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The 690 is $200 more :) I don't think that's chump change for the dual 680, in which I heard the 680 was not much faster than the 670.

Processor is i7 3770 (not K version,) slightly overclocked. So the board is PCI 3.0. I would hope that processor would not be the weakest link. Short of overclocking or extreme models, I could not do better on the processor.

If the game IS CPU bound, I have no simple way to tell, but I could try lowering the turbo number to see what happens. I also don't know, if the turbo is operating on the core running the rendering thread of the game or other critical threads. I don't know how to monitor that.

 

kevin83

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You're right to hope that the processor not be the weakest link, but once you get into high-end crossfire and sli configurations you see bottlenecks start to come from other places. You've limited yourself a good 10-15 fps by not buying the k version, you could overclock it to be at least 4 ghz with ease.
 

michaeljhuman

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Yes, Kevin, I agree with you actually. The problem is, I was out of PC hardware for a long time. I bought my components without knowing all I know now, 6 weeks later (been reading a LOT again.) In retrospect, I would have bought the K! I would say it was a rookie mistake, but I am not really a rookie...just been out of the game a long time.

Actually, I admit I have no idea where all the bottlenecks could occur. It's complex world with 4 cores (8 virtual), turbo mode, and throughput at various stages.

 

schnitter

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I never said you could get a GTX 690 for 800. I said if you are going to spend 800, then you are better off spending the extra 200 and just getting the 690. Two 670's WONT do "very similar performance" no way. Two 680 yes, two 670 no. One video card will dissipate less heat in your system which helps in overclocking. If OP doesn't want to spend extra 200 on his budget then buying the 680 GTX now and buying anotherone later would yield better results.

In any case, 60 FPS or 10000 FPS will look the same on most LCD monitors. Unless you have a 3D enabled or 120hz monitor, then trying to get over 100 FPS on DIRT 3 is useless.

EDIT: @OP, i7 and PCI 3.0 mobo certainly is not CPU bottleneck. Just get a single GTX 680 and there is no game you will have problems running (if running on 1 monitor).
 

michaeljhuman

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The 6950x2 setup does over 60fps on all my games, and I have a 60hz refresh. So I have no actual need for better performance.

This is strictly a more power sort of response.

Maybe it does make sense to spend the $1000, in the sense that it's "only" $200 more. But there is a limit to the money I am willing to spend :)

There may be intangibles to the 690 such as less power and/or less noise which are certainly worth consideration.

 

Azteck

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Well first thing you haven't said what resolution you are running at? If your running 3 screen @ 5760x1080 then 80 fps is not bad.
I myself have 2 6950 2gb cards and they run great and my resolution is 5760x1080.
 


http://hexus.net/tech/reviews/graphics/39605-nvidia-geforce-gtx-670-sli-vs-the-beasttm/?page=5

Apparently they do. They are "very slightly" slower, but since you can buy OC'ed 670's, and many if not most are now, then that would make up the gap if not more.

Depending on the motherboard and airflow, you often find dual cards run hotter than two separate cards, because the two cards GPU's get their own HSF, instead of two GPU's sharing one. However, that will also translate to a little more heat in the case, if you use a card that dumps heat into the case. This is a result of it dissipating more heat which is good for the GPU.

I personally would choose to save money. Actually scratch that, I'd get a single 670 or 680, given the OP is using a single 1080p 60hz monitor.
 

michaeljhuman

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Yes, that's true. Fully aware actually. It's not about being reasonable, as I stated before. And perhaps about ensuring I never drop below 60fps in any game at max settings, now and maybe in the next 2 years of games.

If I was reasonable, I would have bought an i5 and a 7950 and if needed dropped a few unimportant settings down a bit, if needed :)

I may also do multi-monitor (for 3D games, my current dual monitors don't match up for doing it now) if the bug bites me and finances permit one day. But currently, it's really just about benchmarks as I have noted a number of times.

 
Two midrange cards in SLI historically outperform the single top end GPU. For example, the 560 Ti in SLI for $400, beat the $500 580 by 40%. I expect we'll see the same from the 660 Ti.

Outta the box, the stock 690 will top twin reference 670's but twin non reference 670s will top the 690 and and are $200 cheaper. The 670 scales 1.61 in SLI on 3d Mark 11. The Asus TOP scored 9839 and scaled in SLI, that's 15841. The EVGA 690 scored 15023 overclocked to max stable settings.....so for $200 less, you get about 4% more performance outta the 670s in SLI. The 2 cards in SLI will also run a lot cooler with an empty slot between them.
 

michaeljhuman

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My current thinking is that Dirt 3 is CPU bound as some people suggest. I see very little difference between mild overclocking the GPUs and pushing them to the the limits of overclocking I can manage. In both cases, very close to 80fps.

It does seem odd to be CPU bound, if that's the case, with ultra settings, but nothing I have tried gets me much beyond 80fps. I don't have an unlocked CPU sitting around, so no real way to try to boost CPU.




 


If you don't have a 120hz monitor, it probably won't matter one bit. A 60hz monitor can only display 60 FPS worth of frames. With v-sync off, you will see the extra frames melded together with other frames which result in tearing, but may improve the smoothness a tad up to about 80-90 FPS from my experience (but still don't do this because I hate tearing).
 

michaeljhuman

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Yes I understand. I expected more fps though. So I was trying to understand what's going on, because I am curious if I am not going to run into issues with some future game with sufficient power.

Thinking of getting two GTX 670s, just to ensure better performance, but it would be disappointing to do that and find I got no improvement.
 

michaeljhuman

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* Some follow up notes -

* Dirt 3's fps improved to over 100 with different Radeon driver ( seems like some of the drivers, between 12.4 and 12.8 result in the 80fps average
* I did order 2 FTW 670 cards before I learned that the issue was driver related; will still install them and sell the 6950 cards - seems like good set of boards