Introduction
Christmas is coming. Yes, yes, I know it's depressing to hear those words in September (and early September at that), but as the last quarter of any given year shows up the graphics IHVs -- if they've hit a product cycle running and yeilds are good -- will invariably throw out a couple of new value-for-money SKUs in order to grab ever larger chunks of GPU business.That's especially true these days, when Dave Orton or Jen Hsun-Huang blowing their noses is enough reason for a new product launch (no offence!). Production capacity, production costs and market trends mean the marketing teams are always on the lookout for a new pricepoint to launch on, an old product to replace or a chance to hit at the opposition hard with something unbeatable in terms of bang-for-your-hard-earned-buck.
So today sees NVIDIA announce two new products in the high end of the mid-range, launching one with immediate availability to boot, in order to do something with less-than-perfect G71 silicon in one instance, and phase out an existing product with something they think is better in the other. GeForce 7900 GS and GeForce 7950 GT are their names, here's the skinny on them both. Further, we warn you now that this analysis will be short and sweet, given that we've taken a look at GeForce 7-series in depth already from a tech perspective, and G71 is G71. We simply want to show you where it slides into the product stack where price/performance is concerned.
GeForce 7900 GS
First, a refresher on what GeForce 7900 GT is. G71 in full 8/24/16 config, GeForce 7900 GT sits under GeForce 7900 GTX by virtue of clocks and memory size alone, with NVIDIA differentiating their top two single-GPU products not on GPU configuration this time around.So if GeForce 7900 GT is a G71 in full fettle, with 256MiB of memory and at 450/660, GeForce 7900 GS is just the GT with one vertex shader unit and one fragment quad disabled (and all ROPs intact), NVIDIA using defective G71 dice this time around. GS has the same clocks, the same memory size and the same GPU, just a fraction of it is turned off. In table form, for the at-a-glance readers.
| Theoretical Rates for GeForce 7900 GS and GT | ||
|---|---|---|
| NVIDIA GeForce 7900 GS | NVIDIA GeForce 7900 GT | |
| Core Clock | 450MHz (470MHz VS) | 450MHz (470MHz VS) |
| Memory Clock | 660MHz | 660MHz |
| Pixel fillrate | 7.20G pixels/sec | 7.20G pixels/sec |
| Texture sampling rate | 36.0G samples/sec | 43.2G samples/sec |
| Z-only fillrate | 14.4G samples/sec | 14.4G samples/sec |
| Vertex transform rate | 0.82G tris/sec | 0.94G tris/sec |
| VP MADD issue rate | 5.60G instr/sec | 5.00G instr/sec |
| FP MADD issue rate | 31.2G instr/sec | 21.6G instr/sec |
| Memory bandwidth | 56.32 GB/sec | 42.24 GB/sec |
So down on texture sampling, vertex and fragment processing rates in terms of theoretical numbers. It's how that translates into real-world performance compared to GT that we're most interested in, especially as GT looks to be phased out in due course by 7950 GT.
GeForce 7950 GT
GeForce 7950 GT is announced today too, but NVIDIA have asked reviewers to hold back on releasing performance data until the 14th, to coincide with the boards being available at retail. We're allowed to tell you the chip config though, and the other board details. It's G71 of course, in full 8/24/16 splendour, at 550/700 and with 512MiB of on-board memory. That means clocks go up compared to 7900 GT, and board memory size doubles.With 7900 GTX at 650/800, everything else identical, 7950 GT raises NVIDIA's one-from-the-top bar for single-GPU board products where performance is concerned. We'll talk about other board details and pricing as the review progresses.
