Analysis: GeForce 9800 GTX GPU

Posted at: Tuesday 1st April 2008 by Clive Webster

We take a close look at the new GeForce 9800 GTX and its G92 GPU - does the new GPU really deserve to be called a 9-series GTX?

With the performance between the 512MB GeForce 8800 GTS and the new GeForce 9800 GTX being so similar (click here for GeForce 9800 GTX benchmarks) we've ventured under the chunky heatsink to see what's really new.

SPECIFICATIONS
First impressions suggest 'not much' as both GPUs have 128 stream processors, 16 ROPs, 64 texture units and a 256-bit memory interface. The only tangible difference is the clock speeds, and even then, the much newer 9800 GTX only has few more megahertz over the 512MB 8800 GTS. Its core speed is 675MHz, just 25MHz more than the 512MB 8800 GTS, while the stream processors are clocked at 1.688GHz rather than 1.625GHz. If you were expecting a GPU revolution with the arrival of the 9800 GTX, you’ve been badly let down.

Nvidia states that the 'ROP compression system' is more aggressive in the 9800 GTX, reducing the strain on the skinny-looking 256-bit memory interface while the GPU resolves AA and prepares each finished frame for output. However, Nvidia says that this will only come into its own at high resolutions, or with bucketloads of AA. The company also states that the ideal resolution for the 9800 GTX is 2,560 x 1,600, the native resolution of a 30in TFT, but we’re sceptical about the card’s ability to handle games at settings below that, such as 1,920 x 1,200 (as on a 24in TFT).

NEW FEATURES
The other upgrades to the 9800 GTX are support for 3-Way SLI and Hybrid SLI. With a compatible motherboard (i.e. on with a forthcoming Nvidia chipset with integrated graphics), the system can power down the 9800 GTX and use the motherboard’s integrated GPU to render Windows. When a game starts, the microcontroller embedded in the 9800 GTX turns on the card and it takes over from the integrated graphics. However, if you use this technology, you have to route your graphics card’s output via the integrated GPU. It's possible this will lead to a performance hit, as the data could suffer arbitration hold-ups from the PCI-E bus, Northbridge and integrated GPU. We won’t know until we test it, so look out for an update.

The GeForce 9800 GTX itself even looks like a refined 512MB 8800 GTS, with elegant curves rather than disjointed angles between the fan section of the cooler and the heatsink portion. The card is 10.5in in length, the same as the GeForce 9800 GX2, although it isn’t as heavy, weighing in at 'only' 700g. You’ll need two 6-pin PCI-E power connectors for the 9800 GTX, which might make you think it consumes so much energy that it will single-handedly instigate global climate change. In fact, it's quoted as consuming only 6W more power than the 512MB 8800 GTS. Indeed, our test system consumed 319W at peak when fitted with the 9800 GTX, compared to the 322W with a 512MB 8800 GTS installed. Nvidia recommends at least a 450W PSU for a system with a 9800 GTX, and an SLI-certified 650W PSU for two. Even under load, the GeForce 9800 GTX remains pleasantly quiet.