If it were power, you should be able to set all youtr memory BIOS controls to AUTO. that usually gets rid of any customsettings that might have been a problem. If you are alreadya t AUTO then BIOS wouldn't likely be the problem.
As said already, many BIOSes (those without EPP detection and automatic configuration via EPP settings - most motherboards don't use EPP config by default, as not all memory modules use the technology) don't set the Voltage correctly, and when you got a memory module rated for 2.0V (as the XMS2 modules should be rated at) or 2.1V (which the Dominator modules should be rated at) running at 1.8V you're bound to run into problems sooner or later. When pushing the computer hard and you're memory is 0.2-0.3 below it's specified rating there's a high probability of instability.
Memory Voltage settings in BIOS often goes under "Overclocking" settings, or "Performance" settings. I'd strongly recommend you check this, as especially when using more memory modules running them below their specified Voltage can be problematic. (This can't really be understated, so that'd be the third time I mention that by now ^^)
Also, running a system with a full setup of memory modules, especially ones that require some more oomph (2.0V+) can be problematic, no matter if you got everything setup correctly. Many motherboards have problems handling it due to power distribution issues and such. I'd never recommend filling all memory slots with performance memory modules, as the M/B most likely wont be able to handle that. (I've had countless support issues with this in my work, so this is a relatively common occurance.)