X-bit labs

PowerColor RADEON X800 PRO Graphics Card: Modification, Extreme Overclocking and a Duel against Leadtek GeForce 6800 GT (page 3)

Category: Video

by Tim Tscheblockov

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

Increasing the Memory Voltage

So, the graphics processor is ready for my experiments. Now, I will deal with the graphics memory.

Increasing the memory voltage, I found that it practically didn’t affect the overclockability of the memory chips on the PowerColor card. However, the memory chips became much hotter (well, I wouldn’t call them cool at their ordinary frequency, either). Without any cooling of the memory chips, such overclocking threatened to damage the card utterly.

That’s why I chose not to tamper with the memory voltage – the possible reward doesn’t outweigh the risk of destroying the GDDR3 chips with their internal termination circuitry and much higher sensitivity to any overstrain compared to ordinary DDR SDRAM chips.

Anyway, you may be luckier than me with memory on a particular RADEON X800 Pro card. So if you feel like experimenting, examine the snapshot of the internal circuitry and the I/O buffers of the memory chips:

These regulators are based on the standard and widespread ISL6522 chips from Intersil, so there’s nothing extraordinary to increasing the graphics memory voltage on this card.

Installing a Water Cooling System

The core voltage being higher, the GPU consumes more power and generates more heat, nearly in direct proportion to the squared voltage increase. It means that the standard cooling system of the graphics card may not be able to handle the excessive heat during overclocking.

So I replaced the compact, but not very efficient cooler of the PowerColor card with a water-based solution from Thermaltake – Aquarius II:

Now I can be sure the GPU is not going to die of overheat – the card is ready for the tests.