The GeForce GTX 660 Ti Review, Feat. EVGA, Zotac, and Gigabyte
by Ryan Smith on August 16, 2012 9:00 AM ESTCompute Performance
Shifting gears, as always our final set of real-world benchmarks is a look at compute performance. As we have seen with GTX 680 and GTX 670, GK104 appears to be significantly less balanced between rendering and compute performance than GF110 or GF114 were, and as a result compute performance suffers. Cache and register file pressure in particular seem to give GK104 grief, which means that GK104 can still do well in certain scenarios, but falls well short in others. For GTX 660 Ti in particular, this is going to be a battle between the importance of shader performance – something it has just as much of as the GTX 670 – and cache/memory pressure from losing that ROP cluster and cache.
Our first compute benchmark comes from Civilization V, which uses DirectCompute to decompress textures on the fly. Civ V includes a sub-benchmark that exclusively tests the speed of their texture decompression algorithm by repeatedly decompressing the textures required for one of the game’s leader scenes. Note that this is a DX11 DirectCompute benchmark.
For Civilization V memory bandwidth and cache are clearly more important than raw compute performance in this test. Although this isn’t a worst case scenario outcome for the GTX 660 Ti, it drops substantially from the GTX 670. As a result its compute performance is barely better than the GTX 560 Ti, which wasn’t a strong performer at compute in the first place.
Our next benchmark is SmallLuxGPU, the GPU ray tracing branch of the open source LuxRender renderer. We’re now using a development build from the version 2.0 branch, and we’ve moved on to a more complex scene that hopefully will provide a greater challenge to our GPUs.
Ray tracing likes memory bandwidth and cache, which means another tough run for the GTX 660 Ti. In fact it’s now slower than the GTX 560 Ti. Compared to the 7950 this isn’t even a contest. GK104 is generally bad at compute, and GTX 660 Ti is turning out to be especially bad.
For our next benchmark we’re looking at AESEncryptDecrypt, an OpenCL AES encryption routine that AES encrypts/decrypts an 8K x 8K pixel square image file. The results of this benchmark are the average time to encrypt the image over a number of iterations of the AES cypher.
The GTX 660 Ti does finally turn things around on our AES benchmark, thanks to the fact that it generally favors NVIDIA. At the same time the gap between the GTX 670 and GTX 660 Ti is virtually non-existent.
Our fourth benchmark is once again looking at compute shader performance, this time through the Fluid simulation sample in the DirectX SDK. This program simulates the motion and interactions of a 16k particle fluid using a compute shader, with a choice of several different algorithms. In this case we’re using an (O)n^2 nearest neighbor method that is optimized by using shared memory to cache data.
The compute shader fluid simulation provides the GTX 660 Ti another bit of reprieve, although like other GK104 cards it’s still relatively weak. Here it’s virtually tied with the GTX 670 so it’s clear that it isn’t being impacted by cache or memory bandwidth losses, but it needs about 10% more to catch the 7950.
Finally, we’re adding one last benchmark to our compute run. NVIDIA and the Folding@Home group have sent over a benchmarkable version of the client with preliminary optimizations for GK104. Folding@Home and similar initiatives are still one of the most popular consumer compute workloads, so it’s something NVIDIA wants their GPUs to do well at.
Interestingly Folding @ Home proves to be rather insensitive to the differences between the GTX 670 and GTX 660 Ti, which is not what we would have expected. The GTX 660 Ti isn’t doing all that much better than the GTX 570, once more reflecting that GK104 is generally struggling with compute performance, but it’s not a bad result.
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rarson - Friday, August 17, 2012 - link
I might have said that ten years ago, but when I read stuff like "the GTX 680 marginalized the Radeon HD 7970 virtually overnight," I wonder what kind of bizarro universe I've stumbled into.CeriseCogburn - Sunday, August 19, 2012 - link
That's the sales numbers referred to there rarson - maybe you should drop the problematic amnesia ( I know you can't since having no clue isn't amnesia), but as a reminder, amd's crap card was $579 bucks and beyond and nVidia dropped in 680 at $499 across the board...Amd was losing sales in rapid fashion, and the 680 was piling up so many backorders and pre-purchases that resellers were gbegging for relief, and a few reviewers were hoping something could be done to stem the immense backorders for the 680.
So:
" "the GTX 680 marginalized the Radeon HD 7970 virtually overnight,"
That's the real world, RECENT HISTORY, that real bizarro world you don't live in, don't notice, and most certainly, will likely have a very difficult time admitting exists.
Have a nice day.
Biorganic - Saturday, August 18, 2012 - link
Go look up Bias in a dictionary instead of flinging around insults like a child. When the adults converse amongst themselves they like to Add things to the actual conversation, not unnecessarily degrade people. Thanks! @$$-OJamahl - Thursday, August 16, 2012 - link
The point I was making was that Nvidia has seeded overclocked cards to the majority of the tech press, while you had a go at AMD for their 7950 boost.After all the arguments and nonsense over the 7950 boost, hardly anyone benchmarked it but still plenty went ahead and benched the overclocked cards sent by Nvidia. Two AMD partners have shown they are releasing the 7950 boost edition asap, prompting a withdrawal of the criticisms from another nvidia fansite, hardwarecanucks.com
So again I ask, AMD's credibility? The only credibility at stake is the reviewers who continually bend over to suit Nvidia. Nvidia has no credibility to lose.
silverblue - Friday, August 17, 2012 - link
I'm afraid I have to back you up on this one. NVIDIA released not one, not two but THREE GT 640s, and I think people have forgotten about that one. AMD have replaced the 7950 BIOS and as such have overclocked it to the performance level where it probably should've been to start with (the gap between 7950 and 7970 was always far more than the one between 7870 and 7950).Yes, AMD should've given it a new name - 7950 XT as I said somewhere recently - but it's not even two-thirds as bad as the GT 640 fiasco. At least this time, we're talking two models separated only by a BIOS change and the consequently higher power usage, not two separate GPU generations with vastly different clocks, shader counts, memory types and so on.
If I'm wrong, I'm wrong, however I don't understand how AMD's GPU division's credibility could be damaged by any of this. Feel free to educate me. :)
CeriseCogburn - Sunday, August 19, 2012 - link
For your education and edification: amd failed in their card release by clocking it too low because they had lost the power useage war(and they knew it), and charging way too much on release.They suck, and their cred is ZERO, because of this.
Now it not only harmed amd, it harmed all of us, and all their vender partners, we all got screwed and all lost money because of amd's greed and incompetence.
Now amd, in a desperate panic, and far too long after the immense and debilitating blunder, that also left all their shareholders angry (ahem), after dropping the prices in two or three steps and adding 3 games to try to quell the massive kicking their falling sales to nVidia injuries...
FINALLY pulled their head out of it's straight jacket, well, halfway out, and issued permission for a GE version.
Now, maybe all you amd fans have been doing much and very excessive lying on 78xx79xx OC capabilities, or amd is just dumb as rocks and quite literally dangerous to themselves, the markets, their partners, all of us.
I think it's a large heaping of BOTH.
So there we have it - amd cred is where amd fanboy cred is - at the bottom of the barrel of slime.
Galidou - Sunday, August 19, 2012 - link
Anyway, with you AMD fails, always failed and will continue to fail at everything... I don't know if you think people will read your posts like religious madmans and beleive it a 100%, you're making it so exagerated, that it's barely readable.The words nazi and such comes back so often when you go on the madman route, that it's a wonder if anyone gives you any credibility. A little sad because you have nice arguments, you just display them surrounded by so much hate, it's hard to give you any credit for them.
We do exagerate AMD's performance just for the sake of being fanboys, but not to the point of saying such debilitating stuff like you're so good at it. Not to the point of totally destroying Nvidia and saying it's worth NOTHING like you do for AMD. I may lean a little on AMD's side because for my money they gave me more performance from the radeon 4xxx to the 6xxx series. I won't forget my 8800gt either, that was a delight for the price too. But I can recon when a video card wins at EVERYTHING and is doing WONDERS and none is happening now, it's a mixed bag of feeling. between overclockability, optimization on certain games, etc...
When the 8800gt and radeon 4870 came out, there was nothing people could say, just nothing, for the price, they were wonders, trampling over anythingbefore and after but at the same time you said they were mistake because they were not greedy enough moves.
Wanna speak about greed, why is Nvidia so rich, you defend the most rich video card maker in history but you accuse the others of being greedy, society is built on greed, go blame others. Couldn't they sell their GPU at lower prices to kill AMD and be less greedy? No, if AMD die, you'll see greed and 800$ gpus, speak about greed.
CeriseCogburn - Thursday, August 23, 2012 - link
Didn't read your loon spiel, again, not even glossed, part of 1st sentence.I won't tell you to shut up or change what you say, because I'm not a crybaby like you.
AMD sucks, they need help, and they only seem to fire more people.
Galidou - Thursday, August 23, 2012 - link
To date your best argument that repeats itself is ''AMD sucks'' which is something you learn to say when you're a kid. You're not a crybaby ohhh that's new, you keep crying more than everyone else I've seen, TheJian might be a fanboy but you're more related to the fanatic side of the thing.Still, they are the most rich video maker in history, but they still try to manipulate opinions like every company does. Why? if their product is so good and perfect, why do they have to manipulate? I hear you already saying something like: It's because that AMD suck, they suck so much that Nvidia has to make em suck even more by manipulating the stoopid reviewers because the world is against Nvidia and I'm their Crusader.... good job.
CeriseCogburn - Thursday, August 23, 2012 - link
Yes, I've never crapload of facts nor a single argument of note, and your head is a bursting purple strawberry too mr whiner.