X-bit labs

“Cool” and “Quiet” or Anti-Extreme Overclocking Experience (page 8)

Category: Video

by Tim Tscheblockov

[ 02/27/2004 | 04:04 AM ]

Sapphire RADEON 9800 PRO 256MB Ultimate Edition

The last graphics card in our today’s experimental investigation is Sapphire Ultimate Edition of RADEON 9800 PRO. That’s a real graphics monster with its 256MB of DDR2 memory and a huge cooling system from Zalman consisting of two heatsinks connected with a heat pipe. Every memory chip is covered with its own heatsink:

When the graphics card was loaded with some heavy work, the temperatures of the graphics and memory chips became really worrying. My apprehensions came true: after half an hour of work in the Burn mode, there appeared artifacts on the screen – the card was unstable even at its regular frequencies because of unacceptable overheating.

Let’s get to our anti-extreme business. The regulators of the VPU and memory are based on the same chips as by RADEON 9700 and RADEON 9800. So I just show you a few snapshots where the regulators and the connection points for the additional resistors are indicated:

The card doesn’t have a regulator for the termination circuits: they are implemented in the DDR2 chips from Samsung.

I couldn’t achieve any better results. One of the reasons for that is probably the complex wiring of the card with long signal lines, while the graphics memory works at high frequency (700MHz).

As a result, the graphics chip voltage became 8% lower and the graphics memory voltage – 7.5% lower (only for VDD). The card remained stable in our tests with these voltages active.

Here is the card just before we started our tests:

Let’s see if there are any advantages of the small voltages reduction at all:

80-85°C under workload seems to be very warm. Let me remind you that the diagram contains temperature values taken not from the graphics processor and memory chips, but from the heatsink surface.

Having reduced the voltages, we managed to drop the temperature of the VPU and memory by 8-9°C in the Idle mode and by 8-14°C in the Burn mode. The result is pretty good, and the card passed all our tests after the modification, but the temperatures are still dangerously high.

It is indisputable that you should install this graphics card into a good system case or provide some extra air cooling. In other words, it’s quite difficult to turn RADEON 9800 PRO 256MB from Sapphire into a “Cool’n’Quiet” graphics card.