Faster clocks

Traditionally ATI has placed very tight restrictions on what their board partners can and cannot do with their cards in order to achieve certification by ATI. In the past ATI has only approved minor board level changes to the board’s basic design such as adding dual DVI connectors, including VIVO (video-in/video-out) support via ATI’s Rage Theater chip, or swapping out the stock cooler for something more exotic. In fact these are all changes ASUS has employed in their ATI-based cards in the past. If you recall, ASUS was the first board manufacturer to add VIVO support in any Radeon card: before ASUS came along this was a feature only found in All-In-Wonder cards.

Running the graphics card at a clock speed higher than ATI’s reference clock speeds was a strict no-no. ATI was very adamant about this, as they wanted to ensure a consistent performance level across the board, particularly in the wake of criticism received over the wild variations in speeds board partners chose for their Radeon 8500LE cards.

In more recent months however, as ATI and their board partners have seen increasing competition from NVIDIA-based cards such as the GeForce 7800 GTX and 7800 GT (both of which have been fashionably overclocked by a wide range of NVIDIA’s board partners) ATI has relented on this, allowing their board partners a considerable amount of wiggle room on their X800 GT and X800 GTO cards. Clock speeds of retail cards based on both of these GPUs are all over map at the moment.

ATI is now providing the same degree of freedom on the Radeon X1800 XT, and ASUS is the first board partner to cash in on this as their robust Arctic Cooling cooler does an excellent job of keeping the R520 graphics core cool.

ASUS clocks the R520 graphics core on their Extreme X1800 XT TOP card at 700MHz – 75MHz higher than ATI’s stock clock speed of 625MHz. This is an improvement of just over 10%, boosting fill rate from 10 Gigatexels/sec on the stock X1800 XT to 11.2 Gigatexels/sec on the Extreme X1800 XT TOP.

But ASUS doesn’t stop there, as the ASUS overclocks the memory on the Extreme X1800 XT TOP as well, running it at 800MHz (1.6GHz effective), an improvement of 50MHz over the stock Radeon X1800 XT.

It’s important to note that while the board’s memory runs at 800MHz, ASUS uses the same Samsung K4J52324QC memory modules that are used on regular Radeon X1800 XT cards. These modules are rated at 1.2ns so technically ASUS isn’t overclocking the memory, as the modules are good for speeds of up to 800MHz according to Samsung. NVIDIA uses faster 1.1ns memory modules on their GeForce 7800 GTX 512MB cards but these modules are currently in very short supply.

Power connector is routed differently on the ASUS Extreme X1800 XT TOP

Power starts here

Goes down the metal extension

To power all this, ASUS includes an 80-watt external power supply kit, which must be used with the Extreme X1800 XT TOP. ASUS runs a rounded power cable from the board’s external power connection on the back of the board across the top of the card where it rests inside a metal housing. This metal housing also acts as an additional heatsink for the board’s PCB, drawing heat off the card.

Across here...

...and the power supply is connected out here

The 80-watt external power supply

From there the power cable runs across the card’s fan, and finally out to the board’s backplate. Here you’ll hook up the external power supply unit, which is fairly small and fortunately doesn’t generate much heat.

While it sounds complicated, the whole solution is actually fairly elegant, some may even feel it’s easier than reaching inside your case to connect the X1800 card to your system’s power supply unit. After all, with ASUS’ external solution you don’t lose a power connection from your PSU.

This way ASUS can also ensure a consistent level of additional power is going to the card in addition to the power the board receives via the PCI-E graphics slot.