Every new generation of graphics cards has seen the battleground littered with the bodies of the fallen. Whether it's the domination of the 9800 Pro, the GTX280, the HD4870 and HD5870s or the GTX580, every generation has had the winners and the losers.
The original GTX480 was too hot and too noisy, but how power in abundance. This was quickly fixed with the GTX580 which ruled the roost as the fastest single GPU until the release of the awesome HD7970 which has taken up the mantle as the ultimate single GPU card.
Now nVidia are back into the fray with the GTX680, codenamed Kepler. Although it has a new GPU under the hood such was the frantic redesign of the Fermi for the GTX580 that this is actually the first real evolution of the Fermi core ideology.
Has it retaken the crown from the HD7970?
Now a lot has changed with the way that nVidia are solving the problem of supplying outstanding performance without breaking the bank in terms of power consumption and heat. Rather than clocking the bejeezus out of each core they have greatly increased the amount of cores available but left them running at a lower clock speed, thus saving power. However rather than just let this spare power go to waste the GPU now automatically overclocks itself up to the TDP limit so you get the dual benefits of low power gaming without compromising the performance. However, let's just look at the numbers for now and we'll cover the rest as we go.
|Graphics Processing Clusters||4|
|Base Clock||1006 MHz|
|GPU Boost Clock||1058 MHz|
|Memory Clock||6008 MHz|
|Video Memory||2048MB GDDR5|
|Memory Bandwidth||192.26 GB/s|
|Texture Filtering Rate||128.8 GT/s|
The most immediately obvious changes are the low TDP, down from 250W, the insane memory speed (up from 4000 MHz on the GTX580) and the use of 8 SMX units to give a hefty 1536 CUDA Cores.
Whereas Fermi introduced the idea of parallel geometry, Kepler has taken it to the next level with 4 main Graphics Processing Control (GPC) units each containing two Streaming Multiprocessors which are further made up of a ton of CUDA Cores.
We'll let nVidia themselves explain :
Inside the new Kepler GPC resides the next generation Streaming Multiprocessor (SMX). The SMX not only provides more performance than Fermi's SM, but does so while consuming significantly lower power.
Most of the key hardware units for graphics processing reside in the SMX. The SMX's CUDA Cores perform the pixel/vertex/geometry shading and physics/computer calculations. Texture units perform texture filtering and load/store units fetch and save the data to memory. Special Function Units (SFUs) handle transcendental and graphics interpolation instructions. Finally, the PolyMorph Engine handles vertex fetch, tessellation, viewport transform, attribute setup and stream output.
The primary focus of the Kepler architecture is power reduction. By having six times the amount of CUDA Cores than we saw on the Fermi, nVidia have managed to double the amount of performance available from each watt drawn. This fanatical dedication to power saving means that the GTX680 often is running beneath the TDP cap. Rather than just let all this potential go to waste nVidia have introduced GPU Boost, whereby the GPU automatically overclocks itself until it hits the 195W TDP limit, giving you the best of both worlds. Lots of performance but delivered in an ecologically friendly way.
It's not only about power though. The newest 300 series drivers have introduced the ability to enable FXAA via the control panel, enabling it in hundreds more games than were previously available. Further they have developed TXAA which takes advantage of the phenomenal texture performance of the GTX680 to bring Pixar levels of quality to the anti-aliasing.
Finally the latest 300 drivers introduce adaptive VSync. Anyone who turns off VSync to eliminate stuttering when the framerate drops from 60 to 30 will have experienced screen tearing. Equally anyone who runs with it on all the time will have noticed the jerking that occurs when the frame rate dips and the VSync is forced to go from 60 FPS to 30 FPS. Adaptive VSync aims to eliminate that by dynamically turning the VSync on and off so that when the frame rate is above 60 FPS you get VSync on, but as soon as it drops below the magic 60 FPS mark the drivers turn VSync off so you get a much smoother experience.
A quick glance and one would think this was a standard reference design card, and of course in a lot of ways it is. However some subtle design tweaks have meant that all isn't what it seems.
On the right we have, from top to bottom, a GTX570, the GTX680 and a GTX560. As you can see the GTX680 isn't a behemoth, but rather a reasonably sized card.
One of the most obvious changes is the redesign of the power inputs. Instead of side-by-side they are now stacked which allows for better internal placement of the fan and suchlike, as well as a reduction in card size as we saw above.
The business end is much the same as always with two DVIs, a HDMI and a DisplayPort. However it's worth noticing that the GTX680 supports triple-screen 3D from a single card, a vast improvement on earlier cards if 3D is your bag.
Externally at least it looks fairly standard besides the adjustment of the power connector placement. The usual SLI fingers and branding dominate the visible part, as well as the dark PCB.
Beneath the shroud a lot has changed. The heatsink is a complete redesign with the new fin arrangement allowing for greater airflow and hiding some hefty heatpipes. The fan itself contains some acoustic dampening material that should hopefully reduce the whine that smaller fans give and are the primary cause of noise pollution.
Intel Core i7-3960X @ 4.6GHz
ASUS Rampage IV Extreme
Noctua NF-F12 Fans
Windows 7 Ultimate x64
As well as the internal GPU overclocking you can, of course, manually overclock the GTX680. We managed to get it completely stable at a mighty 1215MHz and the Memory to 6110MHz. A pretty handy boost.
The new cooler is a big improvement upon the old reference design, being the magical combination of cooler and quieter. Our overclock came with an overvolt, which brought the idle temperature right up, but the load temperatures remained identical whether at stock or overclocked. The silence is the big thing though. Damn this card is quiet.
3D Mark 11
We all know that there is one number you're all interested in and you can see that the GTX680 just edges out the HD7970. When overclocked things tighten up dramatically. The GTX680 giving 3507 X Marks vs 3521 for the overclocked HD7970.
Compared to the GTX580 it's 33% quicker, which is a monumental increase.
3D Mark Vantage
In Vantage things are, again, very close indeed between the two flagship cards. If this is an indication of what we can expect in gaming tests then this will be decided on points.
At stock the GTX680 is just ahead of the HD7970 and it's only when overclocking that we see the trend reversing, although we're still only talking a handful of frames.
Batman Arkham City
With a hefty dose of PhysX underneath the hood we would expect the GTX680 to rule the roost in Batman Arkham City and so it proves. At stock things are tight but once the GTX680 is overclocked it really moves ahead. However it's worth noting that Batman AC isn't the most reliable test, as otherwise we could argue that the HD7950 is equal to it.
Battlefield 3, for all its faults, is a good test and despite the maximum frame-rates being pretty equal it's clear that on average the GTX680 just has the edge. Not by much though. When overclocked we get the most impressive result with the game staying above 60FPS at all times. Good stuff.
We had a lot of issues with Crysis 2 and EA being their usual unhelpful selves took forever to get it fixed. However it's back up and running and so we can return it to our test bench. This does mean that we're missing all of the latest Radeon results, but it does clearly demonstrate the extra performance nVidia have brought with their latest card as it demolishes the GTX580 and gives the GTX590 a damn good run for its money.
Dirt 3 is odd to say the least. Whether the newer generations of ForceWare drivers aren't helping it or what we don't know, but obviously the GTX680 isn't so bad that it's outperformed by nearly everything in the graph, including the GTX560. Still the results are what they are, so if you like hooning about on the mud then the Radeon is clearly the option to go for.
Far Cry 2
The Dunia engine behind Far Cry 2 has always preferred the AMD cards and the latest generation doesn't change that. The GTX680 is much closer to the HD7970 than previous efforts have been, but the HD7970 still just shades it.
It's pretty amazing how close the two flagship cards are, but once again the HD7970 just about edges ahead of the GTX680 in average frame-rate. However that doesn't tell the whole story because the minimum frame-rate on the GTX680 is much better leading to an overall smoother experience, even if the ultimate performance appears to be lower.
We've often commented how Metro 2033 is a game that just adores a dual-GPU setup and is slack on a single card. So we were very pleased when the HD7970 was capable of giving us good playability even on a single GPU. With the GTX680 things are pretty much back to normal with the Kepler card not being that impressive.
Resident Evil 5 - DX9
As we return back to Africa and Resident Evil 5, we see that the GTX680 is once again close to the Gigabyte version of the HD7970, but a bit behind the reference design. Although when dealing which such high frame-rates it's churlish to pick too many holes.
Resident Evil 5 - DX10
Switching to the DirectX 10 rendering path we see very similar results with the GTX680 just behind the Gigabyte and a fair bit behind the reference HD7970s.
Improvements to the tessellation performance is one of the big bullet-points from nVidia and at stock you can certainly see the GTX680 is capable of chewing through Unigine. However when both it and the HD7970 are overclocked things become much closer indeed.
Ramping up the anti-aliasing actually brings the HD7970 closer to the GTX680 at stock and moves it ahead when the cards are overclocked. Although the maximum frame-rate of the GTX680 hints at a lot of available performance once the non-reference cards hit the market.
The Witcher 2
Finishing up with a near perfect demonstration of what's been obvious throughout this review, it's almost impossible to separate the GTX680 and HD7970.
So much to cover, so little time.
There are two sides to the GTX680. On the one hand there is the elements that we can test right now, and will make a difference to the average person, and on the other we have the wealth of features that are an attempt to futureproof it to some degree.
If you're only here for pure gaming performance and number crunching then the GTX680 certainly has performance in spades. It's nearly identical to the HD7970 in the numbers we saw throughout our testing and only in a couple of instances was the HD7970 ahead. Probably the most surprising thing was how the big PhysX title (Batman) doesn't really see much of a benefit when compared to the Radeon. The high tessellation performance was another improvement that nVidia were quick to emphasise and yet in Unigine it's nearly impossible to split the two flagship cards.
Where the GTX680 really shines is in the power consumption and cooling departments. Whereas the HD7970 paid for its high performance with a huge power draw the GTX680 is an enormous improvement requiring nowhere near the same levels of power. The redesign of the cooler has also paid dividends. The card is as warm at stock as it is when overclocked and in both scenarios it's ultra-quiet. A true pleasure for the ears.
Stuffed with technology is always a good thing but there is some oddness with the good. The automatic overclocking definitely works well as throughout our tests the stock performance was very good indeed. The card might have the fastest GDDR5 we've yet seen, but from our results it doesn't make that much of a difference to performance. Equally the Tessellation improvements might be there, but the Unigine results don't lie. The other big tweak is the TXAA anti-aliasing which, from the screenshots at least, looks like we might finally be rid of the jaggies. Except nothing supports it yet and the FXAA it replaces never became that widespread by developers. PhysX is a similar story. The game development world is far too cut-throat for a company to risk alienating half the population by throwing their lot in with a proprietary technology, especially with the backwards technologies on consoles hindering PC gaming so much. So potentially it has a lot of brilliance going for it, but we'll have to wait and see before judging how useful those will be.
What cannot be denied is that the GTX680 is another great card from nVidia. It's the Fermi concept refined and polished to a high-sheen and delivers high performance at low power, which surely is the way forwards. In terms of actual frame-rates it's nearly identical to the HD7970 and for the first time in a long while you truly can throw your hat in with whichever company you prefer and know that you aren't compromising anything. The performance, low power, quietness and general usability ensure that the GTX680 is worthy of our OC3D Gold Award.
It's a great time to be a geek.
Thanks to nVidia for supplying the GTX680 for review. Discuss in our forums.