For the TPower X58 and X58A memory OC problem, this is related to the CPU version.
If use i7 920 C0 stepping CPU, the maximum Uncore frequency is locked at 2133 MHz.
Then memory can only support to 1333 MHz, which is half of the max Uncore frequncy.
Please see attched picture for detail.
If use i7 920 D0 stepping CPU, the Uncore frequncy is unlock.
Then memory can easily OC to 1333 MHz by BIOS setting.
Adding more memory voltage can make system more stable.
Please see attched picture for detail.
