AT Exclusive Preview: The GeForce 7800 GS Hits the Scene
by Derek Wilson & Kristopher Kubicki on November 22, 2005 8:00 PM EST- Posted in
- GPUs
The Card
The NVIDIA GeForce 7800 GS in its current state is based on the G70 chip (listed as revision A1) with cut down pixel and vertex pipelines. The board layout is based on the 7800 GTX 512 board with all the RAM located on the front side of the PCB. Of course, the RAM used is the same type used on a 7800 GT (1GHz 8x32 GDDR3) rather than the super fast 1.7GHz 16x32 GDDR3 chips used on the 7800 GTX 512. This also means the board is equipped with 256MB of RAM using a 256bit interface.
We took a look at the pipeline info using RivaTuner. What we have is a 16 pixel 6 vertex pipeline configuration. This is one quad and one vertex pipeline less than the 7800 GT (20 pixel and 7 vertex pipelines).
We did have to do a little bit of driver hacking to get the card installed properly. The nv4_disp.inf file needed to be edited to add support for the hardware ID reported by the cards bios. We got the hardware ID from the device manager properties:
PCI\VEN_10DE&DEV_0093&SUBSYS_030E10DE&REV_A1\4&19AD4D94&0&0020
All we needed to do to add support for this card was to add two lines in the nv4_disp.inf file:
%NVIDIA_G70.DEV_0093.1% = nv4_NV3x, PCI\VEN_10DE&DEV_0093
and
NVIDIA_G70.DEV_0093.1 = "NVIDIA GeForce 7800 GS (hacked)"
It will be quite obvious where these lines go in the file, and the string in quotes is the driver description that is shown in the device manager (and RivaTuner). This string doesn't affect what the NVIDIA driver page shows, as it pulls its information from the hardware itself.
Once these lines are added to the .inf file, the driver could be installed with no problem. After making sure everything was setup correctly, we checked the clock speeds to make sure everything looked right. We ended up seeing a 375 MHz core clock and 1 GHz memory clock:
So now we know what we've got: a 375MHz G70 core with 16 pixel pipes and 6 vertex pipes connected to 256MB of 1GHz GDDR3 using a 256bit interface. This setup looks a little bit like an overclocked 6800 GT on the surface (of course, with G70 you get transparency AA and more efficient pixel pipes). Given what we know about the 6800 GS (it performs like a stock 6800 GT) and the 7800 GT (it will be faster than this with 20 pixel pipes, 7 vertex pipes, and a higher core clock), we can easily say that the 7800 GS will perform right in between these two parts.
Before we take a look at performance, let's take a look at our test system.
The NVIDIA GeForce 7800 GS in its current state is based on the G70 chip (listed as revision A1) with cut down pixel and vertex pipelines. The board layout is based on the 7800 GTX 512 board with all the RAM located on the front side of the PCB. Of course, the RAM used is the same type used on a 7800 GT (1GHz 8x32 GDDR3) rather than the super fast 1.7GHz 16x32 GDDR3 chips used on the 7800 GTX 512. This also means the board is equipped with 256MB of RAM using a 256bit interface.
We took a look at the pipeline info using RivaTuner. What we have is a 16 pixel 6 vertex pipeline configuration. This is one quad and one vertex pipeline less than the 7800 GT (20 pixel and 7 vertex pipelines).
We did have to do a little bit of driver hacking to get the card installed properly. The nv4_disp.inf file needed to be edited to add support for the hardware ID reported by the cards bios. We got the hardware ID from the device manager properties:
PCI\VEN_10DE&DEV_0093&SUBSYS_030E10DE&REV_A1\4&19AD4D94&0&0020
All we needed to do to add support for this card was to add two lines in the nv4_disp.inf file:
%NVIDIA_G70.DEV_0093.1% = nv4_NV3x, PCI\VEN_10DE&DEV_0093
and
NVIDIA_G70.DEV_0093.1 = "NVIDIA GeForce 7800 GS (hacked)"
It will be quite obvious where these lines go in the file, and the string in quotes is the driver description that is shown in the device manager (and RivaTuner). This string doesn't affect what the NVIDIA driver page shows, as it pulls its information from the hardware itself.
Once these lines are added to the .inf file, the driver could be installed with no problem. After making sure everything was setup correctly, we checked the clock speeds to make sure everything looked right. We ended up seeing a 375 MHz core clock and 1 GHz memory clock:
So now we know what we've got: a 375MHz G70 core with 16 pixel pipes and 6 vertex pipes connected to 256MB of 1GHz GDDR3 using a 256bit interface. This setup looks a little bit like an overclocked 6800 GT on the surface (of course, with G70 you get transparency AA and more efficient pixel pipes). Given what we know about the 6800 GS (it performs like a stock 6800 GT) and the 7800 GT (it will be faster than this with 20 pixel pipes, 7 vertex pipes, and a higher core clock), we can easily say that the 7800 GS will perform right in between these two parts.
Before we take a look at performance, let's take a look at our test system.
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JarredWalton - Tuesday, November 22, 2005 - link
Despite what you might think, I can guarantee that this article is not at all sanctioned by NVIDIA. (I'd go so far as to say they're probably really unhappy that the info got leaked to us.) I wouldn't say the same for whoever provided the card, though - some company like ASUS, Leadtek, etc. (no, I don't know where it came from) might have slipped us the card to see the reaction. Very little information comes directly from NVIDIA, ATI, etc. without an NDA. We get most of the "secret" stuff through numerous other channels.We're hardware enthusiasts, and many people have been wondering about lower priced G70 parts. Whether or not this card actually sees the light of day soon (if at all) is most likely going to depend on chip yields for the G70. If a decent number of cores are failing tests on two quads, it makes more sense.
The 7200 and 7600 (or whatever they end up being named) are due out in the next few months. Depending on price/performance, there may or may not be a niche for this product. If it's too fast for the price, it would hurt sales of 7600. We'll see what happens.
ariafrost - Tuesday, November 22, 2005 - link
Good job on getting this info so quickly, and especially on obtaining the card. AT caught 'em napping.vijay333 - Tuesday, November 22, 2005 - link
product line's getting even more cluttered, but good info nonetheless. surprised AT would be able to post this info without running into legal difficulties, even if a NDA wasn't actually signed...since the card is now 'hot property', I'd be happy to take it off your hands ;)