Bolt-on RAM/VRM sinks for 4850/4870?

[iandh]

I removed the fan sitting over the top of the card and just had the 2 x 120mm blowing over the fan as seen here. (in this pic the fan is still on the HD4870, but I'm trying to show the location of the other 120mm that blow air across my PC).

So without the fan on the card, but the two other ones not so far away Furmark went to 117+C. This proves that airflow in a case is not enough to cool the VRMs. You will need specific airflow OVER the VRMs. Now keep in mind my card is running 850 Mhz core. If you are overclocked you need more airflow than just the case flow.

Those temps disagree with my watercooled card, which was around 90C with two fans mounted in the same style, but twice as far away as yours and undervolted to 1000RPM.

If I had to guess, I would say it is because the fin density is so high on the sinks that you have mounted. That high fin density only works well with direct cooling/high airflow situations. For any effectiveness in low/medium airflow situations, you need a lower fin density like on my sinks. With high airflow, I would say my sinks and the ones you have mounted would perform much more similarly.

Do you have any way of measuring your internal case temperature with the side panel on?




edit: Just fyi the sinks could be four times larger, and probably would still get over 100C without the direct cooling. Just the name of the game with this card. Anyone wanting to agressively OC should be running monster sinks or FC blocks.