Nvidia GeForce 8800 GT graphics chip
Nvidia's bang-for-buck winner?
Review Nvidia’s new 'G92' graphics chip is based on the 'G80' used in the GTS, GTX and Ultra versions of the GeForce 8800, and is a die-shrink that moves from the part from its predecessors' 90nm fabrication process to 65nm.
There are other changes inside the chip, which gains the VP2 video engine and bitstream processor used in the junior members of the GeForce 8000 family. Fans of HD video won’t have to work their CPU quite so hard in future. Nvidia also tells us that the 8800 GT gains an AES128 encryption/decryption engine for HDCP content.
MSI's NX8800GT: cool runner
Thanks to the extra hardware, G92 contains more transistors than G80, with the count increasing from 681 million to 754 million.
Other new features include a move from PCI Express (PCIe) 1.1 to 2.0, and the adoption of HDCP for content copy-protection over dual-link DVI. If you have a socking great display, the dual-link connection can drive a resolution of 2560 x 1600.
In terms of the core speed, memory speed and Stream processors, the GT is positioned right between the current GTS and GTX models.
|8800 GTS||8800 GTS||8800 GTX||8800 Ultra||8800 GT||8800 GT|
|Memory||320MB GDDR 3||640MB GDDR 3||768MB GDDR 3||768MB GDDR 3||512MB GDDR 3||512MB GDDR 3|
The new GT core runs at 600MHz, which is faster than both the GTS and GTX. The GDDR 3 memory runs at the same 1800MHz as the GTX and there are 112 stream processors - more than the GTS, less than the GTX - which run at the same 1500MHz as the 8800 Ultra.
Asus' EN8800GT: a single-slot 8800 at last
The one notable difference with 8800 GT is a change in the memory controller. The GTS has a 320-bit controller for the 320MB or 640MB of GDDR 3 memory, while GTX uses a 384-bit controller for its 768MB of memory, but the GT employs a 256-bit controller for 512MB of memory. Despite the faster memory speed used by the GT the memory bandwidth is narrow than it is on the GTS, significantly slower than the GTX and half that of the Ultra.
Changing the fabrication process of G92 has reduced the amount of power used by the chip and this has led to a significant change in the design of the graphics card. Previous 8800s used a double-slot design that exhausted hot air through a vented bracket to the outside world. The cooler on the GTS/GTX was very efficient and quiet but also very bulky so it was no small proposition to install a pair of 8800s in SLI.
Card widths: GT (left) and GTS
By contrast, the new 8800 GT is a single-slot card that vents its heat inside your PC case from an exit at the top of the shroud next to the SLI connector. The cooler on the GT is as quiet as the cooler on the double-slot cards so once it is sealed inside your case the emitted noise is lower, although you may well need to employ an extra case fan to deal with the heat. The heatsink/cooler on the 8800 GT is made from aluminium and copper with a plastic shroud that clips on to add some cosmetic appeal and to duct air to the correct places. The six-pin PCIe power connector has moved from the top edge of the card to the back where it is tucked away inside the cooling shroud.
During our testing, the cooler got very hot and was at least 20°C hotter than the 8800 GTS we used for comparison. However, the graphics chip remained cooler and was happy to overclock, which suggests that the GT's cooler is very efficient.
The GT doesn’t replace either the 320MB or the 640MB GTS yet. It is cheaper than both models so we wanted to see how it sits in the current line-up. We had 8800 GT-based boards from Asus and MSI, both of which are reference designs. However, the Asus EN8800 GT is clocked at the reference 600MHz/1800MHz speeds while the MSI NX8800GT-T2D512E runs at 660MHz/1900MHz with Stream processors that run at 1650MHz.
Nvidia's reference 8800 GT in SLI configuration
We had no trouble overclocking the Asus to 690MHz/2000MHz, while the MSI went a little further to 700MHz/2040MHz. Out of the box, the MSI had a definite advantage over the Asus but once we had overclocked both cards there was nothing to choose between them in terms of performance. You pay an extra £12 for the Asus which comes bundled with Company of Heroes: Opposing Fronts while the MSI is packaged with Colin McRae DiRT, so your buying decision is likely to come down to which game you prefer.
We compared the two 8800 GT cards with an Asus EN8800GTS that is a basic model with 320MB of memory. The GTS performed surprisingly well on driver 169.02 but it was hosed down in 3DMark06 by both GTs at standard clock speeds.
Nvidia GeForce 8800 GT - 3DMark 06 Results
Longer bars are better
However, the GTS overclocked by a huge amount, from 510MHz/1580MHz to 660MHz/1840MHz, and the resulting performance was comparable to the Asus GT at standard speed. Once we’d overclocked both GT cards, the GTS was beaten again but the margin was fairly small. The benefits of the new GT were clear: it drew 30W less power at the socket than the GTS and took up half the space inside the PC.
Nvidia GeForce 8800 GT - system power draw
Power draw in Watts
Shorter bars are better
Naturally, we plugged both GT cards together in SLI but the results were unimpressive. Our inclination is to point the finger at the drivers as SLI rarely seems to work properly on new cards.
Nvidia's GeForce 8800 GTS is a firm favourite among gamers for its combination of superb gaming power and excellent value for money. The 8800 GT adds some handy features, a sprinkling of performance and a single-slot design at a price that's irresistible.