Overclocking and Stability
Overclocking is, by its very nature, unpredictable. Even if you buy a CPU according to make, model, and week of production, there's no telling how much extra performance you might or might not get through overclocking. This is definitely true in in the case of the Core i7 920 we used when testing this board—the CPU runs just fine at stock speeds but overclocks with the grace and agility of a one-winged epileptic duck.
This is less than fun, and it makes it difficult to push a motherboard given the limited range of multipliers that keep the CPU's clock sufficiently low. In this case, however, a recalcitrant processor doesn't seem to have been the issue. The X58A-UD3R was nominally stable at a Base Clock of 180MHz, but increasingly unstable from the 180-200MHz range. Higher voltages would, we think, have stabilized the board at the 200MHz mark, but we'd already hit the maximum recommended voltages for the CPU and QPI links.
The QPI speeds were one factor in the system's instability above 180MHz. Gigabyte offers just four options—Slow, x36, x44, and x48. System stability improved if we used the "Slow" setting, but this slowed the interconnects to just 100MHz. The X58A-UD3R is certified for the 6.4GB/s QPI speeds higher-end Core i7 processors use, but any setting that pushed the transfer rate above 7GB/s noticeably increased the likelihood of a crash.
Overall, we'd rate the X58A-UD3R as a fairly good overclocking board, if not an exceptional one. All of the right BIOS options are baked in, voltage control is extremely granular, and the board recovers easily from incorrect voltage/frequency settings.
As we noted in our Test System information, we wanted to do more than simply put the X58A-UD3R through a standard set of paces. After the normal benchmarks were complete, we loaded the board with six DIMMs of dual-bank Elpida 2GB DDR3-1333 modules.
The more DIMMs (and by extension, the more banks) of RAM that are present, the harder it becomes for the memory controller and motherboard design layout to handle the load. Loading all six DIMM slots with dual-bank RAM let's us see if the board is stable under stressful conditions. We looped PCMark and 3DMark Vantage several times each to ensure system stability.
The X58A-UD3R passed our tests with flying colors. It had no trouble running at 1333MHz with all six DIMMs installed and took the RAM up to 1667MHz without a hitch or the need to raise CAS/RAS latencies. When it comes to memory stability, this board is a rock.