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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nserra - Wednesday, November 23, 2005 - link
the 7800GTX512 is the card to buy because it's much faster than the others. ;)I want one but with 256MB memory, and less than 399$. Call it 7800GTX256 i dont care.
What happen to the Ultra (naming), doesnt sound good?
coldpower27 - Wednesday, November 23, 2005 - link
Your basically dreaming here, since the MSRP of the 7800 GTX 256 is 499US now, best we could hope for is GTX 256 Rev.2 at MSRP 549US.lexmark - Wednesday, November 23, 2005 - link
Could you guy possibly replace doom3 benchmarks with CoD2? The game is growing cobwebs now! :) Quake 4 should account for doom3 since its built with an optimized doom3 engine.KHysiek - Wednesday, November 23, 2005 - link
I think it needs a bit faster memory on release version. Something like 1.2GHz would be nice.coldpower27 - Wednesday, November 23, 2005 - link
The problem is both a lower product and a higher product, have the exact same memory bandwidth of 32GB/s, so it doens't look like they have much flexibility with the bandwidth. Unless you want to pull an ATI, and have memory bandwidth at different levels, across the entire line like X800 Series.Wesleyrpg - Wednesday, November 23, 2005 - link
I'm a bang for your buck sorta guy. Seems like its going to be a great card should it ever get released!How about the important stuff, does it overclock well, and how aboout those estra pipelines, are they unlockable?
DerekWilson - Wednesday, November 23, 2005 - link
Its a tough sell to even claim that the 7800 GS will ship with this pipeline and clock speed configuration, let alone to say that retail units will function similarly to this random early sample we happened to get our hands on.Up to 8 pipelines could be unlocked on this unit with RivaTuner, but if NVIDIA starts building G70 based silicon with only 16 pipes that capability could go away. And just becuase something can be unlocked doesn't mean it will work.
Finding out how overclockable this part will be is a big reason we want to see this card make it to market.
gibhunter - Wednesday, November 23, 2005 - link
Fine, since I've been a reader of AT for about 7 years (this is the first PC enthusiast site I visit every day) I'll give you guys a benefit of the doubt.Next time you write an article about an unanounced card, try not to sound so defensive. It makes you look guilty.
DerekWilson - Wednesday, November 23, 2005 - link
I didn't defend anything :-)My opinion on the subject is that the truth doesn't change if someone decides to believe a something else. And if you can't take us at our word in our articles then there's nothing I can say that will change your mind in our comments.
I would hope that our track record has proven us to be trustworthy and plain spoken with our readers. But that doesn't mean I want people to stop questioning us and keeping us honest.
Paratus - Tuesday, November 22, 2005 - link
Are any of these tested with AF?