NVIDIA's release of the GeForce GTX 660 Ti last week represented an obvious, straightforward move into shoving its high-end Kepler GPU architecture into a chip with a lower price. Differentiated from the GTX 670 by losing some backend muscle and now available for £230 from selected retailers, stock-clocked cards are a reasonable bet.
The next product to receive the Kepler architecture makeover will be the GeForce GTX 660 (non-Ti). Rumours have previously suggested that this upper-midrange card is to ship with a cut-down die, and not just another hobbled GK104 part that's used in all of NVIDIA's premium consumer GPUs.
But these rumours of a pared-down die designed primarily for this segment are seemingly at odds with NVIDIA's own information. You see, the firm has published specifications of a GeForce GTX 660 OEM part on its site, and the consensus is that it's powered by an increasingly-castrated GK104 die.
| GPU | GeForce GTX 680 (2GB) |
GeForce GTX 670 (2GB) |
GeForce GTX 660 Ti (2GB, 3GB) | GeForce GTX 660 (1.5GB/3GB) |
|---|---|---|---|---|
| Die codename | Kepler GK104 | Kepler GK104 | Kepler GK104 | Kepler GK104? |
| DX API | 11.1 | 11.1 | 11.1 | 11.1 |
| Process | 28nm | 28nm | 28nm | 28nm |
| Transistors | 3.54bn | 3.54bn | 3.54bn | 3.54bn? |
| Die Size | 294mm² | 294mm² | 294mm² | 294mm²? |
| Processors | 1,536 | 1,344 | 1,344 | 1,152 |
| Texture Units | 128 | 112 | 112 | 96 |
| ROP Units | 32 | 32 | 24 | 24? |
| GPU Clock (MHz) | 1,006 (1,058) | 915 (980) | 915 (980) | 823 (888) |
| Shader Clock (MHz) | 1,006 (1,058) | 915 (980) | 915 (980) | 823 (888) |
| GFLOPS | 3,090 | 2,459 | 2,459 | 1,896 |
| Memory Clock (MHz) | 6,008 | 6,008 | 6,008 | 5,800 |
| Memory Bus (bits) | 256 | 256 | 192 | 192 |
| Max bandwidth (GB/s) | 192.3 | 192.3 | 144.2 | 134 |
| Power Connectors | 6+6 | 6+6 | 6+6 | 6-pin |
| TDP (watts) | 195 | 170 | 150 | 130 |
| GFLOPS per watt | 15.84 | 14.46 | 16.39 | 14.58 |
| Current MSRP | $499 | $399 | $299 | $249? |
Going along with the notion that the OEM card mirrors a retail GPU's specification, which is a reach, NVIDIA looks to chop another SMX unit - dropping from a possible eight to six - thus diminishing cores to 1,152 and texture-units to 96. Frequencies are knocked down to 823MHz core and 5,800MHz memory, with the latter interfacing at a 660 Ti-like 192 bits.
Conjecturing somewhat, the GTX 660 should perform at around 80 per cent of the speed exhibited by GTX 660 Ti, with the exact performance ratio dependent upon gaming title. Assuming this comes to pass, GTX 660 will fight it out against AMD's price-cut Radeon HD 7850/70, currently available from £150 or so.
Lower performance is married to a lower TDP of 130W, too, enabling NVIDIA to release this card with a single 6-pin PCIe connector - GTX 660 Ti probably could, but NVIDIA doesn't take the chance, especially when the card can draw more when its Power Target is raised. GTX 660 (OEM) also arrives with a standard dual-slot form factor and four-display output common on decent Kepler cards.
Of course, the retail GTX 660 could simply be using the most-complete implementation of a mid-range die, one equipped with a maximum six SMX units. All will be revealed in the coming days and weeks, we're sure, so the mid-range graphics space is about to get interesting all over again.
