The largest difference between the PCI Express and AGP interface is the maximum bandwidth that can be obtained. AGP 8x can only offer 2.133 GB/s peak, while PCI Express x16 can offer 4 GB/s. As has been beaten into our heads ferociously by marketers for the past couple of years, this means that PCI Express is able to theoretically offer double the performance of AGP cards. It is important to remember, though, that this is all in a theoretical situation where there is 100% efficiency. For the most part, the benchmarks that were run today show us that AGP and PCI Express perform practically the same in the mainstream market segment.

What we are seeing in the video card market is similar to the situation of hard drives. Although the SATA 3.0 Gbit/s interface has a bandwidth three times that of Ultra DMA ATA 133, the actual performance difference between the interfaces is quite small, meaning we still haven’t been able to fully exploit all that the SATA interface has to offer.

This situation is being mirrored in the video card market creating a dilemma for users with older AGP systems. They are left to make the choice to buy a completely new system or just upgrade the video card to a newer AGP one. In most cases, we saw very little performance difference between AGP and PCI Express cards. There were some tests where there were small performance differences; however, the PCI Express interface’s victory margin wasn’t large enough to actually draw a conclusion off of. In fact, there were also a handful of tests where AGP came out to be the victor.

The final decision really falls on budget. It is a known fact that upper end performance AGP cards are scarce. We did see some at CeBIT this year , but we still need to get some more information on when products like these will start hitting the market along with their pricing.

There are a number of things to keep in mind before actually making a decision. First and foremost, upper end cards are always being released in PCI Express 16x first, meaning you won’t be able to find a GeForce 8800 GTX AGP right now or anytime soon. This means that if you really want the latest cards immediately in your computer, you might want to look into a new system.

The cost of a new system is also something to keep in mind. Because of the market transition from DDR to DDR2, there won’t be many components in your system you’ll be able to reuse. This fact alone will hike up the price of a new computer. The AGP cards we reviewed today, on the other hand, come for less than $200, much less than the cost of getting a completely new PC.

The bottom line is this. If you have the choice of upgrading your old AGP system, or instead making a completely new system on a tight budget that only has a mainstream card like the X1950PRO, from what we’ve seen today you would be better off just upgrading to a new AGP card. Spending the money for a completely new PCI Express system that has a midrange video card is pointless considering that there isn’t much of a performance benefit at the moment going from AGP 8x to PCI Express. This will allow you to, at least for right now, enjoy the best of both worlds. You’ll be able to enjoy better gaming performance at a low cost and successfully extend the life of an older AGP system.