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BFG Tech's GeForce 7800 GS OC AGP graphics card


The GeForce 7 comes to AGP
— 8:00 AM on February 2, 2006

OWNERS OF PC SYSTEMS with AGP slots have been getting the shaft lately when it comes to graphics cards. NVIDIA released its GeForce 7 series this past summer, and ATI has introduced not one, but two generations of high-end Radeon X1000-series GPUs. Yet neither company has seen fit to introduce a fast new AGP card, somehow figuring that the upgrade market would prefer PCI Express so overwhelmingly it didn't matter. That seems to be a rather harsh assessment given the fact that one can slide an Athlon 64 X2 into a reasonably decent Socket 939 AGP mobo like the Asus A8V and get a dual-core CPU upgrade.

Fortunately, NVIDIA and BFG Tech are looking to right that wrong by introducing the GeForce 7800 GS OC, which brings the shader power of the GeForce 7 architecture to an AGP slot near you—or at least some of that shader power, anyhow. The GeForce 7800 GS is based on the same G70 GPU that powers other 7800-series graphics cards, but it's cut down to a portion of the full functionality of a GeForce 7800 GTX. Does this G70 "lite" still have what it takes to dominate the AGP graphics upgrade market? Let's find out.

The card
Our lovely contestant today is the GeForce 7800 GS OC card from BFG Technologies. This blue-and-green beauty features a single-slot cooler, an AGP connector, and a four-pin Molex auxiliary power connector that's friendly to older power supplies.


BFG's GeForce 7800 GS AGP


M-M-M-Molex!

NVIDIA recommends at least a 350W power supply unit to keep the 7800 GS stable and happy, which shouldn't be too much of a stretch for any AGP-based system still worth keeping in 2006. This card features one DVI and port one VGA port, presumably because those frozen in time enough to prefer AGP are also not picky about getting digital signals to two LCD displays at once. I suppose that's a safe bet. BFG does include a DVI-to-VGA converter in the box with the card, along with a Y-cable for the Molex power connection.

NVIDIA says cards like this one should be in Best Buy stores by this coming Sunday, and they should be available from online vendors by the following Monday. Judging by what we've seen already, we'd expect "e-tail" availability to happen even sooner than that, though. Prices should range from $299 to $349.

So what do you get for that price? Well, let's look under the hood and see.


NVIDIA's PCI Express-AGP bridge chip (foreground) and the G70 GPU

The GeForce 7800 GS packs an honest-to-goodness G70 graphics processor—the same one found in the GeForce 7800 GTX. In order to make this PCI-Express-native GPU talk over an AGP port, NVIDIA pairs it up with the HSI bridge chip; this is the same chip that made it possible for AGP-native GPUs like the NV40 to work on PCI Express cards back in the day. The bridge chip is simply translating in a different direction here, mediating between a PCI Express GPU and AGP core logic.

Unlike on the GeForce 7800 GTX, though, the G70 graphics processor on the 7800 GS isn't operating at full capacity. In its wisdom, NVIDIA has seen fit to disable vast portions of that big GPU you see pictured above. They've chopped down the G70's 24 pixel shaders by two "quads," so that 16 pixel shaders remain. Two of the GPU's eight vertex shaders have been lobotomized, leaving a total of six. And they've nixed half of the ROPs responsible for pixel output, so that the 7800 GS has only eight.

Now, the reasons for this hack job on the G70 GPU could be several. Sometimes, a portion of a chip just doesn't come out working properly, but the GPU can still be used in a partial configuration like this one. It's possible NVIDIA has a load of G70 chips sitting in a warehouse somewhere that aren't quite up to the task of acting like a full 7800 GTX. Other times, chipmakers deactivate portions of a chip purely for product segmentation reasons. We really like the GeForce 7800 GT, another partially realized G70 product, because it's a better value for the money than the full GTX. In the case of the GeForce 7800 GS, NVIDIA's motivations for cutting down the G70 to a 6 vertex shader/16 pixel shader/8 ROPs config may be some combination of a desire to move chips that aren't 100% perfect and an intention to meet the needs of a lower-end market. I dunno.

The upshot of it all is that the GeForce 7800 GS should still be one of the fastest graphics cards ever to slide into an AGP slot, but it won't be a titan of graphics performance like a five-hundred-dollar 7800 GTX.

NVIDIA's recommended clock speeds for the 7800 GS are 375MHz for the core GPU clock and 1.2GHz for the card's 256MB of GDDR3 memory. As is its custom, BFG Tech has chosen to push the envelope a little bit and offer an "overclocked" in the box version of the 7800 GS, which is what we're reviewing here today. Of course, because this is a BFG Tech card, the "overclocked" speed carries no real risk with it. BFG's GeForce 7800 GS OC comes with a lifetime warranty and a pipeline to some of the best tech support in the biz.

Sizing up the AGP options
Compared to other high-end AGP cards, the 7800 GS's combination of clock speeds and execution resources is... not bad. Sixteen G70-class shader pipes at 400MHz ought to outdo the GeForce 6800 Ultra's sixteen pipes at the same speed. And the 6800 Ultra is a pretty good match for the Radeon X850 XT, ATI's most prominent high-end AGP graphics card. The Radeon X850 XT is selling online for under $400, so it's probably the 7800 GS's closest competition when both price and performance potential are taken into account.

In order to put the GeForce 7800 GS into proper context, we've tested it against a range of the latest high-end PCI Express graphics cards, as well as one of ATI's best AGP cards. Unfortunately, I didn't have an AGP version of the Radeon X850 XT on hand, but I did have the older Radeon X800 XT Platinum Edition, which runs at the exact same core clock speed and nearly the same memory clock speed as the Radeon 850 XT and uses the same GPU architecture. (In fact, the X850 XT was just a tweak of the X800 series intended to help bring wider product availability among high-end cards.) So consider the older Radeon X800 XT PE in our benchmark results as a stand-in for the Radeon X850 XT, if you will; its performance should be virtually identical.

The GeForce 6800 GT has been another favorite in the AGP graphics world. NVIDIA recently introduced the GT's direct replacement, the GeForce 6800 GS, which delivers almost exactly the same performance as the GT for less money. AGP versions of the 6800 GS are selling for around $200, and the 7800 GS will have to distance itself from the 6800 GS in order to justify its higher price tag. We've included the PCI-E version of the 6800 GS in our tests, so you may want to keep an eye on those scores.

Now, let's see whether the 7800 GS AGP can make a case for itself as the best AGP upgrade option, and whether that option is as compelling as the abundance of fancy new cards for PCI Express systems.