Quote from: Basiley on May 21, 2011, 08:58:30 AM

no puppose.
saves about 5W but cost some MH/s(about 10-40MH/s drop, depend deep of downclocking and GPU model. ~20MH/s for 250 Mhz on 5870, for example).
slightly improve cooling situation for GPU's with badly designed power subsystems[VRM's/IC's without heatsinks and without strong airflow], unsuitable for mining anyway.
if you care about GPU health put extra-fans in case instead. of [better]invest to water-clooling system. for both GPU, GPU subsystem, CPU, mobo chipset, with external radiator[without fan. huge, expensive, but silean and efficent beast]and even with optional heatsink for PSU[relatively rare product]

Did you read my post? Your saying it "saves about 5W." Have you actually MEASURED this? In my case turning the memory clock down 100Mhz I observed an INCREASE in wattage by about 20-30W!

With my 5830's, turning down the memory clock from 1000Mhz to 175Mhz decreased power consumption by 40-50W (2 cards)! Not only that but my hash rate went up as well!

Quote from: redicarus on May 21, 2011, 08:55:34 AM

I have my 5850 set to 344MHz to get the Mhash boost, never noticed any issues with performance outside of games.

Card model? OS? Have you measured wattage of the rig?