When Nvidia launched the GeForce GTX Titan in February, it set a new record for the fastest single GPU graphics card performance – and tagged the card with a correspondingly high price tag. At £830, the 7.1 billion transistor GPU was out of reach of all but the richest of gamers. However, Nvidia is now debuting the Nvidia GeForce GTX 780, a Titan-derived card. It offers most of the GTX Titan's performance, but at two-thirds of its hefty price tag.
Nvidia has trimmed a number of features to bring the price tag down from £830 to £550. The GTX 780 has 2,304 cores compared with Titan's 2,688 cores, a drop of approximately 15 per cent. Texture mapping units are also somewhat lower, down from 224 to 192. The total number of raster operators (ROPs), however, is still the same at 48.
The chip's core clock is in the same ballpark as the Titan's (863MHz base, 902MHz boost, compared to the Titan's 836MHz base, 875MHz boost). What this means is that the GTX 780 has most of the Titan's raw horsepower, as well as the Titan's 384-bit memory bus and 6Gbps of DDR5 bandwidth.
The total amount of RAM, however, has been trimmed, down to "just" 3GB. This simply isn't much of a problem given that most games are still programmed in 32-bit and are therefore incapable of using more than 4GB of GPU memory in any case.
The other casualty of the step-down is full speed double-precision floating point (like previous GeForce products, the GTX 780 will execute DP code at 1/24th of native clock speed). Hyper-Q and Dynamic Parallelism, two of the high-end features from GK110, remain enabled in the GTX 780, and the chip still supports Compute Capability 3.5 rather than GK104's 3.0. This can matter to certain real-world performance tasks, including Bitcoin mining, though GK110-based cards are still far behind AMD in that regard.
Compared to the Nvidia GeForce GTX 680, the GTX 780 is a marked step forward. The new card has 50 per cent more cores, 50 per cent more texture mapping units, and 50 per cent more render outputs than the older GK104-based solution. This is significantly offset by the lower clock speed; the GTX 680 ran at 1,006MHz standard with a 1,058MHz boost clock. That's a 15 per cent difference between the GTX 680 and GTX 780, which ought to leave the newer card 25 per cent to 35 per cent faster than last year's model. The base memory configuration has also been bumped up to 3GB from the GTX 680's 2GB. That matches AMD's HD Radeon 7970, and it's a solid amount. Presumably we'll see a handful of GTX 780 cards pushing back to 6GB, the same way some vendors have built 4GB GTX 680 GPUs.
Our performance comparisons were run on a rig powered by an Intel 3770K Ivy Bridge CPU, 16GB of DDR3-1600, a 256GB OCZ Vector solid-state drive, and a 27in Asus VG278HE monitor at 1,920 x 1,080. The GTX 690 performance was simulated using a pair of GTX 680s in SLI; tests have demonstrated that the performance delta between the two configurations is essentially nil. All of our tests were run at 1,920 x 1,080 resolution with maximum details set. Multi-sampled antialiasing was activated when available and turned up to 8x if possible.
The GTX 780's speed boost over the GTX 680 varies depending on the game. In Civilization V's Late Game View, the GTX 780 was 12 per cent faster than GTX 680 (100 frames per second or fps vs. 89 fps). In Metro 2033, that advantage jumped to 43 per cent (45 fps vs. 31.3 fps). In Metro: Last Light, Metro 2033's just-released sequel, the GTX 780 was 22 per cent faster, at 38 fps vs. 31 fps. In BioShock Infinite, the GTX 780 was 16 per cent faster than the GTX 680 (82 fps vs. 70 fps).
If you intend to game at 1,920 x 1,080 resolution, the difference between the GTX 780 and the GTX Titan is often tiny. The GTX Titan was 6 per cent faster in Metro 2033 (48 fps vs. 45 fps), 7 per cent faster in BioShock Infinite (88 fps vs. 82 fps) and 3 per cent faster in Civilization V (103 fps vs. 100 fps).
Performance against a single AMD Radeon 7970 was a bit more interesting. In games like Shogun 2, the GTX 780 torched the AMD card 69 fps vs. 38.5 fps. In Metro 2033, however, the AMD 7970 was actually faster at 56 fps vs. 45 fps for the GTX 780. Hitman: Absolution was another strong win for AMD – the Radeon 7970's 72 fps beat out all the GeForce cards. Games like Arkham City and BioShock Infinite favour Nvidia, with the GTX 780 coming in at 82 fps against the Radeon 7970's 68 fps in the latter.
The final performance aspect we want to discuss is the topic of frame latencies, or the question of long it takes to draw each successive frame. Historically, this has been more of an issue for AMD than Nvidia, and it's a bigger problem with dual-GPUs than when single cards are tested. This, however, isn't an absolute – higher frame rates can still matter, and AMD's performance in this area is improving. Here's an example of GPU frame latencies in Metro: Last Light, as graphed by the open source FRAFS tool, using FRAPS data. The following graphs show the GTX 680, GTX 780, and the dual-GPU Radeon 7990 (click on the images to enlarge).
Nvidia GeForce GTX 680:
Nvidia GeForce GTX 780:
AMD Radeon HD 7990:
In this case, the dual-GPU was noticeably smoother, thanks to fewer frame latencies that break the 33.3ms (30 fps) barrier. However, there are other games where this isn't true – Shogun 2: Total War, for example, is a title where AMD still noticeably lags Nvidia in this respect.
If you were looking at buying a Titan card for £830, the Nvidia GeForce GTX 780 for £550 is probably a great deal. The performance gap between the GTX 780 and GTX Titan is quite small at 1,920 x 1,080, and while we expect it would grow modestly at 2,560 x 1,600, it's not going to suddenly skyrocket. This makes the GTX 780 a great option for someone who was already eyeing a GTX Titan and now wants to save a few hundred quid.
In fact, the only users who will seriously benefit from a Titan as compared to a GTX 780 are the handful of gamers looking to build multi-monitor rigs (at which point you probably want two Titans, not just one), or anyone who has a serious use for the GTX Titan's full-speed double-precision floating point.
The GTX 780 is clearly faster than the GTX 680, but it commands a hefty price premium. In our suite of tests, the GTX 780 was, on average, 1.21 times faster than the GTX 680, while costing 1.45 times as much. That's not unusual at these price brackets and there's definitely a market for these kind of products, but if you're searching for the best price/performance point on the market, the GTX 780 isn't it.
Comparisons against AMD products are even more lopsided. The non-GHz edition of the Radeon 7970 can be picked up from around £300 online, and with the HD 7950 as low as £230 now, a pair of them would run £460 – with four free games tossed in to boot, courtesy of AMD's "Never Settle" program. This is where the frame latency issue raises its head, however – if AMD's dual-GPU solutions could be absolutely counted on for delivering smooth playback, we'd say a pair of HD 7950s would likely trump the single GTX 780. With AMD making progress but not being quite there yet, this is less of a certainty.
One thing is certain, though – high-end cards have always been about luxury as much as performance, and if you've been looking for a mini-Titan at a better price, you're going to be happy with the GTX 780. It’s as simple as that.
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