X-bit labs

PowerColor RADEON X800 PRO Graphics Card: Modification, Extreme Overclocking and a Duel against Leadtek GeForce 6800 GT (page 5)

Category: Video

by Tim Tscheblockov

[ 07/15/2004 | 12:55 PM ]

Overclocking the PowerColor RADEON X800 Pro

Before benchmarking the card, I first performed a few experiments, steadily moving from its nominal frequencies to the maximum possible. I wanted to check out how the higher core voltage and the installation of a water cooling system affect the overclockability of the graphics card. To question the card’s stability at overclocking, I ran Unreal Tournament 2004 Demo, Halo and Far Cry, one by one, without pauses. The results follow:

So, I achieved 630/1150MHz frequencies at extreme overclocking.

The maximum frequency of the graphics core was 530MHz with the standard cooler. By mounting the water system from Thermaltake, I pushed the ceiling up to 560MHz. Increasing the voltage by 0.05v, I increased the frequency by 10MHz more. After that, the maximum GPU frequency at overclocking was increasing practically linearly, according to the voltage.

The maximum voltage I supplied to the graphics core was 1.68v. Higher voltages led to the graphics card’s turning off in the hardest stretches of the tests. Yes, it did turn off, rather than hang from overheat (we’ll talk about overheat shortly). The controller chip of the GPU power regulator can keep track of the consumption current of the GPU and it just stops supplying any power after this consumption exceeds an acceptable range.

So, the maximum frequency of the graphics core was 630MHz (32.6% above the nominal frequency) at 1.68v voltage (20% above the nominal). Not bad, actually.

The die of the RADEON X800 graphics processor has an integrated thermal diode, and the card from PowerColor has a monitoring circuitry, so I checked what temperature the GPU had at extreme overclocking. To load the graphics card, I started Unreal Tournament 2004 Demo in the 1600x1200 resolution with enabled 4x full-screen anti-aliasing and 16x anisotropic filtering. Before taking the temperature data down, I was catching the bots on the Torlan map for about 20 minutes. The following diagram shows you the results:

With the standard cooler, the GPU temperature (the red line) was over 60°C even at the regular frequencies! This may not be very dangerous for the graphics card, but it is too much in comparison with the water cooling system. Interestingly, I never noticed the fan of the PowerColor card to accelerate to its maximum speed. Even when the card was overclocked, it would work at half of its capacity. Probably, that’s the way of ATI’s engineers to care about our sensitive ears – the graphics card is practically silent – but anyway I don’t think it is right to endanger the GPU.

The “ambient” temperature (the orange line in the diagram) corresponds to the sensor on the PCB. The ambient temperature goes down suddenly with the water cooling system and never gives any reason for worries afterwards, even at the highest frequencies and GPU voltage.

So, you can overclock the RADEON X800 Pro without any fear after installing a water cooling system. The GPU temperature thus remains low even after voltage adjustments. It is quite possible that higher voltages (in the range of the acceptable, of course) combined with extreme cooling systems would allow reaching higher frequencies, but I doubt the 12-pipelined RADEON X800 Pro can soar up to the level of the RADEON X800 XT.

A simple calculation tells that you should overclock the RADEON X800 Pro to 693MHz to reach the same pixel performance as the RADEON X800 XT Platinum Edition has. This may be possible as a short-term experiment, but I doubt the graphics card will live long working like that. You’ll use up the liquid nitrogen or the graphics processor too soon. :)