With several units already released 'on the quiet', early looks at the '670 have starting coming in and by all accounts this is a card set to shake things up. The Nvidia GTX 670 not only bests the HD 7950 as expected, but also appears to pull convincingly ahead of the HD 7970; this would leave AMD's fastest playing catch-up with Nvidia’s second fastest (single) GPU.
The hardware comes in as predicted; Nvidia's latest puppy being armed with 1344 ‘CUDA cores’ married to 2GB of GDDR5 via a 256-bit bus. Reference clocks appear to be 915 MHz base / 996MHz boost, with the memory running at the same 6008 MHz speed as in the GTX 680. The biggest surprise of Nvidia’s Kepler pudding then, is simply how it appears to perform. Tweaktown
, unfettered by any NDAs (Non-Disclosure Agreements) with Nvidia, has already taken the card through its paces on beta drivers. Normalising these results to the HD 7970 shows Nvidia beating out AMD in six of eight tested games:
This does mesh with what we've seen from other sources and seems to indicate a very solid win for Kepler, which is without doubt a more efficient architecture than its AMD competition. Some significant questions do remain however around price; we may never be sure what proportion of manufactured Kepler cores are imperfect and thus how expensive each Nvidia part truly is to make. The proportion that are fully usable (the 'yield') is an extremely closely guarded secret, but suggestions swirl that a lot less Keplers are viable as compared with AMD's Southern Islands cores. Part of the beauty (and the main reason for the existence) of 'cut-down' cards like this however is that they are designed to only use a majority of the core - in this case seven of the eight 'SMX clusters' As with previous generations, imperfect cores will likely be 'recycled' for use in the GTX 670. Thus somewhat ironically because of lower yields on the GTX 680 there is more potential for good '670. This seems strengthened by the amount of stock confirmed in stores and apparently occasionally bursting out of them to reach customers' hands early, not to mention the relatively low (sub 7970) price they commanded.
The only real caveat to a win by the GTX 670 then is that these results are 'at stock speeds’. The Tahiti core in the HD 7970 and 7950 is renowned for overclocking, with 20 plus percent improvements over stock being common. We’ve previously reported that AMD has plans to lift the stock speed of the HD 7970 to 1GHz, which makes sense as a direct response by the Red Team to Nvidia's latest. These 'GHz edition' HD 7970s should be able to equal the '670. While it is certainly good to see AMD making more of the performance of its top GPU available for those who prefer not to tinker, it could be better for existing 7970 owners. These improvements likely won't be delivered via driver update, but rather with revised hardware and BIOS'. Although potentially miffing (i.e probably angering) current owners, on the positive side AMD's new GHz edition 7970 should be capable of further overclocking given their improved silicon. This is important as the GTX 670 will likely be a capable overclocker should Nvidia not artificially restrict it.
Atomic has contacted AMD querying whether existing 7970s will be 'updated' and as to dates. Their response was a decisive 'no comment' on (although implicitly by wording a confirmation of) any GHz edition, possibly to not dissuade people from buying their current stock models. Overall Atomic considers it very unlikely that existing 7970s will be sped up by AMD; a revised HD 7970 that matches the GTX 670 and some displeased early-adopting AMD customers caught in the middle is the likely lay of the land once the dust settles.
As a last twist - there is a possible resolution to exactly why the '670 PCIe power connectors appear mid-card, rather than towards the end as is traditional. In short it appears the entire end quarter of the card may be made of a fan surrounded by empty space. This would be something of a first for reference cards and it does clash with previous PCB shots, so for now some sense of mystery does remain (which of course keeps the magic alive).
What seems certain is this: May 10th will see a lot of GTX 670s out there and they'll match what AMD has on offer. Atomic will as always be on hand with a full review post release.