At stock voltage, idle temperature under both blocks was 29°C, only 8°C over ambient. At this temp, the PWM controlled pump was registering 2200rpm. Once full load was applied and the system run for ten minutes, pump speed climbed as high as 3350rpm, while the temperature under the XTL block registered 49°C and the HD block was 2°C less.
Increasing voltage by two tenths and bumping the speed up to 4.3GHz causes the idle temperature to rise, but here we see a 2°C difference between the two blocks. The spread increases to a 4°C difference at full load, with the XTL block allowing the CPU to exceed 60°C. Pump speed registers from 2375rpm at idle, up to 4325rpm under load, nearly reaching the maximum 4500rpm ceiling. Despite the higher temp, the system was still stable using either block, however it's likely that under certain circumstances the cooler-running Apogee HD could yield a higher overclock.
Let's wrap things up with some final thoughts and conclusion.