BIOS options
Core i7 overclocking is a brave new world, with all sorts of extra multipliers and voltages with which to fiddle. Even this early in the game, both Gigabyte and MSI have their respective BIOSes relatively up to speed. There are a few key differences worth noting, however.

Unless you feel like dropping a grand on an Extreme Edition with an unlocked upper multiplier, Core i7 overclocking comes down to how high you can push a system's base clock. Gigabyte and MSI serve up plenty of base clock options, with the Eclipse topping out at 400MHz and the UD5 pushing the ceiling to a ridiculous 1200MHz, both in fine-grained 1MHz increments.

The X58 Eclipse's BIOS overclocking interface

While increasing the base clock will pump up the processor's core speed, it also increases the speed of the chip's uncore component and its QuickPath Interconnect, both of which we'd like to keep running as close to their stock speeds as possible. Only the Gigabyte board provides explicit control over the uncore multiplier, although to be fair, this control is somewhat limited. If you want to adjust the board's memory bus multiplier, you have to use an auto uncore multiplier, otherwise the memory bus setting doesn't take. Fortunately, the auto setting works well enough. The MSI board seems to do a good job of managing the uncore multiplier on its own, too, even if doesn't expose this functionality to end users.

On the QuickPath front, the UD5 and Eclipse both offer QPI link speed options. However, only the former allows users to crank the link speed beyond the processor's default value, which for the Core i7-920 is a 36X QPI multiplier that yields a 4.8GT/s link speed. Overclockers will be more interested in slowing the QuickPath link, and both BIOSes oblige with a "slow-mode" option that drops the QPI multiplier to 24X.

Per-channel timing tuning courtesy of Gigabyte

Memory multipliers bring us to an interesting little roadblock that Intel has built into its 920 and 940 processors. While the 965 Extreme has no problem running its memory faster than 1066MHz, provided proper multipliers are available in the BIOS, the 920 and 940 are effectively locked to a memory bus speed of 800 or 1066MHz. The UD5 doesn't even offer higher multiplier options with a 920 installed, and while the Eclipse does, we couldn't get them to work with our 920 processor and OCZ DDR3-1600 DIMMs at either 1333 or 1600MHz.

While neither board will allow users to circumvent Intel's hard limit on Core i7 memory speeds, both offer more memory timing controls than even most seasoned enthusiasts will know what to do with. Gigabyte pushes the envelope further than most here, providing individual timing control for each of the UD5's three memory channels.

Loads of voltage options on the EX58-UD5

Despite the fact that Intel quite explicitly states that running memory bus voltages higher than 1.65V risks serious damage to Core i7 processors, both the EX58-UDT and X58 Eclipse offer memory voltages well in excess of 2V. There are plenty of CPU voltage options available, too, alongside a long list of chipset and other voltages to tweak. Gigabyte serves up a few more voltages than MSI here, but both boards have more than enough overvolting options for even extreme overclocking, with plenty of granularity, too.

MSI's superior fan speed controls

The presence of ample overclocking and memory tweaking options is pretty much a given with high-end enthusiast boards. However, mobos with robust fan speed controls are still few and far between, which is particularly surprising considering how obsessed many enthusiasts have become with having their rigs running as quietly as possible. Automatic fan speed control on the EX58-UD5 is limited to a toggle switch for the processor fan that supports three- and four-pin fan configs. MSI does much better on this front, allowing users to set a target processor temperature and minimum processor fan speed. The X58 Eclipse's BIOS also provides static fan speed controls for three system fan headers, with options to run those fans at 50, 75, or 100% of their default speed.

Specifics on specifications
We've consolidated all the key specifications of the EX58-UD5 and X58 Eclipse below.