Intel 820 'Camino' Chipset

Looking at the AGP slot on an 820 motherboard, you’ll immediately notice the absence of the "notch" we’re used to seeing on AGP 2X cards as you can see by the picture comparison to your right. This "notch" is absent because it allows for a method of selecting the 1.5v operating voltage of an AGP 4X card instead of the 3.3v operating voltage of AGP 2X cards on which the pins, that correspond to where this notch would be located, are missing.

The 820 chipset is the first Intel chipset to boast support for the 4X transfer mode of the AGP specification which offers twice the amount of available bandwidth as the 2X transfer mode did for 1.06GB/s worth of bandwidth dedicated to your graphics adaptor alone.

Now don’t let this number fool you, because the transition from AGP 1X to AGP 2X yielded a similar theoretical performance increase and resulted in a real world performance increase that was barely noticeable. So what will the transition from AGP 2X to AGP 4X yield?

The performance numbers our benchmarks have been showing indicate a performance increase, on average, of about 0.9% in 3D games. We can easily dream up synthetic benchmarks to show off the potential of the 1.06GB/s transfer rate of AGP 4X, but until games start actually using more larger textures we won’t be seeing too much of an improvement with AGP 4X.

The one area you will probably see improvement in is where there would normally be a lot of texture thrashing to and from system memory. In this case, with an AGP 2X graphics card, you would be able to transfer textures back and forth at 528MB/s and in the case of AGP 4X that number would jump up to the 1.06GB/s we discussed earlier. As games use larger and larger textures, the performance benefits of AGP 4X will be easier to notice. But at this point in time, don’t expect to see any huge performance increase just by sticking your old TNT2 into an 820 board.

Currently, the only card that we can use to test AGP 4X performance is the NVIDIA TNT2. Although the Matrox Millennium G400 and G400MAX boast AGP 4X compliance, the original G400 cards did not support the specification which was not finalized at their time of production. This unfortunately means that if you were one of the few that bought the first G400 cards, you’re stuck at a 2X transfer mode unless Matrox can come up with a workaround in the card’s firmware. Whether or not that is possible is still up to the engineers at Matrox to decide. The G400 chip itself is AGP 4X compliant.

Not even all TNT2s support 4X transfer modes. Remember all of the debate as to whether or not the TNT2 you were buying would be AGP 4X compliant from a little while back? It turns out that the same situation exists with older and newer TNT2 boards. The first sign of this was when Diamond began shipping their V770 and V770 Ultra cards with new jumpers to enable/disable AGP 4X. These cards have no problem functioning in AGP 4X mode as long as you set the jumpers properly, but the older boards without the jumpers are stuck in 2X mode unless a workaround in the firmware is developed. Whether that is possible or not still isn’t known.

The true test for AGP 4X performance will be when cards are specifically designed with the specification in mind, the first of which being NVIDIA’s GeForce 256 followed by the S3 Savage 2000 later this year. If you are interested in seeing whether or not your card will natively support the AGP 4X specification, we put a few of our TNT2s to the test to see if they passed or failed the AGP 4X test. Keep in mind that these boards are all relatively old boards and were manufactured around the release of the TNT2 chipset and the individual manufacturers may or may not have enabled AGP 4X since then on later boards.

This is by no means intended to be a comprehensive list, but it is worth looking at, especially if you were one of the first to buy any of these cards: