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The BIOS contains the same Extreme Edition features that we got with the D975XBX2. In the Performance section you can adjust the CPU and memory clock speeds and voltages but the range of adjustments is slightly tighter than those offered by the Taiwanese companies. By default the CPU voltage is 1.325V for a Penryn QX9650 with a range of 1.2875V-1.60V however you can use CPU Voltage Offset to add an extra 0.3V over and above your selected CPU voltage setting. Enhanced Power Slope ramps up the current to the CPU but it's a simple On/Off control and there's no indication how much difference it makes. FSB Voltage is 1.20V by default (range 1.10V-1.50V) and MCH/ICH voltage starts at 1.25V and can goes as far as 1.70V.
You can run your DDR3 memory speed up to 1,600MHz which will certainly require extra juice so a voltage range of 1.50V-2.50V in 0.04V steps fits the bill nicely.
Overclocking an Intel motherboard is meant to be a simple task as the Intel Desktop Control Centre allows you to change settings within Windows instead of tinkering in the depths of the BIOS. The DX38BT promises a new dawn on this score as users of the D975XBX2 are limited to version 3 of the software in Windows Vista (version 2 in XP) but DX38BT allows you to use the new version 4. The software isn't included on the driver disc so we headed to the download page and downloaded the v4.0 Beta however the software wouldn't run on our system even after we'd updated to the latest BIOS which is specifically meant to fix a problem with DCC. Hmm, not good.
We overclocked manually and found that the DX38BT simply didn't want to play ball with our QX9650. We used the MSI X38 Diamond for comparison and found that it would happily run at 3.51GHz on a 390MHz front side bus but the Intel board would only allow us to raise the clock multiplier by one step. Raising the front side bus by more than a handful of Megahertz was a distinct no-no which rendered the overclocking features a trifle irrelevant.
This sums up the DX38BT in a nutshell. If you're running a Kentsfield processor there's no reason to move to from P965 or P35 to X38 and if you have any plans for a 1,600MHz Penryn processor the Intel DX38BT won't work. If you're happy with a QX9650 at near-stock speeds then the DX38BT is a winner but that feels like a small and exclusive club.
Perhaps that explains why the DX38BT is relatively cheap compared to other X38 models on the market and it even comes with a copy of Ghost Recon Advance Warfighter as an added bonus.
Intel has rather shot itself in the foot by giving us a sniff of the 1,600MHz QX9770 processor as it effectively made the DX38BT obsolete before it went on sale. It's a decent bit of kit that looks the part and delivers rock-solid performance but it's time has already passed.