The default core and memory clock speeds for the Radeon X1650 XT are 575 MHz and 690MHz respectively, and this is what the iSilence II model is set at. At these speeds, HIS found that they could use a completely passive cooling mechanism. On their IceQ Turbo, they cranked up the speeds to 630/770 and slapped on a big, honking cooler to get the job done. That left us with two cards, one standard and the other pre-overclocked. Using the ATI tray tool we set out to see how far each card could be pushed. We had the highest hopes with the iSilence II, since we already know that the threshold should be at least what we saw with the IceQ Turbo. Indeed, the core topped out at a similar speed, 631 MHz, while we were able to continue with the RAM as high as 837MHz. The IceQ Turbo had less overhead left available, and after some tweaking we settled for a 654 MHz clock on the GPU and 851 MHz on the memory.
As can be expected, the overclocked iSilence II results were just a bit better than the stock speeded IceQ Turbo. While the core clock speed was almost identical, the 837 MHz that we reached with the memory allowed us to gain just over 100 points in 3DMark06, and an extra frame in F.E.A.R. By the same token, we were able to push up the IceQ Turbo from 630/770 MHz to 654/851 MHz and get even more improved scores. In neither case we weren't able to really come close to the X1950 Pro, which is a shame since the price point of all three cards will certainly become a factor in our final judgment.