It goes without saying that PCI Express is the interface of choice for all new graphics cards and this was evident since last year when the bulk of the new GPU variants debuted only on this interface. When you factor in the possibilities of operating dual graphics cards in parallel and the fact that all new motherboards support the PCI Express interface, it is a no-brainer for GPU designers, board manufacturers and the graphics card vendors to shift their lineup accordingly. While all new personal computers and systems setup henceforth would be based on PCI Express, you can't deny the fact that AGP based systems have been around for years and there is a sizeable upgrade market out there. Just like the PCI graphics card market in the distant past, there are a good many AGP based systems that are perfectly suitable for all kinds of uses and the AGP interface is certainly going to linger around for a long time to come.
While there are a good many AGP graphics cards in the market for all price brackets and needs, the interface bridging chips developed by ATI and NVIDIA respectively have helped to widen the AGP variety available to consumers. NVIDIA's GeForce 6600 GT for example is a native PCI Express GPU, but coupled with NVIDIA's High Speed Interconnect (HSI) chip, it is also available on the AGP interface and has been the hottest selling mid-range performance graphics card for a long while. ATI's Radeon X1000 series made its debut in November and coupled with ATI's Rialto interface bridging chip, a select few graphics card vendors have offered the Radeon X1300 and Radeon X1600 PRO for the AGP platform this year. Though these offer some of the newest features touted in the graphics card industry, the top performing AGP graphics card title still belongs to ATI's Radeon X850 XT Platinum Edition and being the best, it is also very dear at the US$400 to US$500 bracket.
In the green corner, NVIDIA no longer produces the GeForce 6800 Ultra GPU, leaving the GeForce 6800 GT as the highest performing AGP part, though not anywhere as fast as ATI's Radeon X850 XT series. November 2005 saw a brand new GeForce 6800 GS variant and while it was warmly welcomed in the PCI Express market for its 'GeForce 6800 GT'-like performance at an enticing price point, the AGP version didn't quite receive the same salutation. This is because the AGP version was based on the NV40 GPU and clocked at 350/1000, whereas the PCIe version had the NV42 GPU and was clocked at 425/1000. The entry of the GeForce 6800 GS also marked the end of the standard GeForce 6800 and at US$200, the GS is quite a worthy option.
NVIDIA once avowed that their new GeForce 7 series would solely be the mainstay of the PCI Express platform, but with the HSI bridge chip concoction available at their whim, NVIDIA can at anytime cater to the AGP platform according to market forces. After all, ATI still had the upper-end of the AGP segment for upgrade options and we had a tiny persistent notion at the back of our mind that NVIDA might rival them once they had the right part. We knew that it had to be a GeForce 7 derivate for there's none in the GeForce 6 series to rival ATI's Radeon X850 XT series.
And speak of the devil, NVIDIA quietly hard launched a new GeForce 7 SKU on 2nd of February 2006 for the AGP platform, the GeForce 7800 GS. An interesting point here is that the GeForce 7800 GS is exclusively an AGP only product. While there have been older leaks and previews of it in the PCI Express form, NVIDIA has iterated that they have no plans for such at this point of time.
The new GeForce 7800 GS is still based on the same G70 core that's used on the GeForce 7800 GT and the GTX variants, but the GS has only 6 vertex Shader processors and 16 pixel pipelines. The GT and GTX have 7/20 and 8/24 Shader processors and pixel pipelines respectively. The differences don't just stop there as the Raster Operation Pipeline (ROP) units too have been reduced to eight (versus 16 on the higher-end GT and GTX brothers). Sounds like a configuration of the GeForce 6800 class? Don't forget, the G70 GPU has a higher processing capability than the NV40 GPU clock for clock and has increased floating-point performance. Would this be a good contender on the high-end of the AGP scene? On the other hand, the reduced ROP count doesn't look like it would do any good for antialiasing performance. In any case, you'll soon find out first hand just how well the GeForce 7800 GS fares not via a reference card, but a fully retail worthy card with the MSI NX7800GS-TD256. On a side note, the specifications of the GeForce 7800 GS presents itself as an ideal option on PCIe front, seated between the GeForce 6800 GS and the GeForce 7800 GT and one wonders when NVIDIA intends to close this gap. No matter, we detail the basic specs of the GeForce 7800 GS and a few close AGP comparisons to keep in mind that would come in handy for later performance evaluation:-
|GPU/VPU||NVIDIA GeForce 7800 GS (AGP)||NVIDIA GeForce 6800 GT (AGP)||NVIDIA GeForce 6800 GS (AGP)||ATI Radeon X850 XT Platinum Edition (AGP)||ATI Radeon X1600 PRO (AGP)|
|Core Code||G70 + HSI||NV40||NV40||R480||RV530|
|Transistor Count||302 million||222 million||222 million||160 million||157 million|
|Manufacturing Process (microns)||0.11||0.13||0.13||0.13||0.11|
|Vertex Shader Pipelines||6||6||5||6||5|
|Pixel Shader (Rendering) Pipelines||16||16||12||16||12|
|Peak Texture Fill Rate (Mtexels/s)||6,000||5,600||4,200||8,640||6,000|
|Z Compare Units||8||16||12||16||8|
|Memory Clock||600MHz (1200MHz DDR3)||500MHz (1000MHz DDR3)||500MHz (1000MHz DDR3)||590MHz (1180MHz DDR3)||390MHz (780MHz DDR3)|
|DDR Memory Bus||256-bit||256-bit||256-bit||256-bit||128-bit|
|-||-||-||-||256-bit (for memory reads only)|
|Molex Power Connectors||1||1||1||1||NIL|