I would like to max it out with the fastest and as much memory possible which is 24-GB. The Asus Memory QVL list appears to be a year old and recommends the Kingston KHX1600C9D3K3/12GX (XMP) which is about $360 for 12 GB (3x4). If I buy 4 GB memory that is not on the Asus QVL list but has the same timing, voltage, and latency; am I taking a gamble with stability or compatibility issues? The current memory I have is the Patriot DDR3 2000 6MB (3x2). According to the QVL list, this MB will only support 3 sticks at this speed. However, if I buy DDR3 1600, this board will support 6 sticks of memory.
Also, my current P6X58D Premium has an i7-960 3.2GHz Quad-Core. Will I see much improvement in speed/performance (gaming) if I go with a Six-Core?
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CPU... You will see little to no difference with the hex core in gaming. It benefits highly level HD Video / AutoCAD type work.
As for memory... You will see no benefit in gaming with 24GB of RAM. 6GB is still the standard and more than enough Going with 24GB will only increase the likelihood of an unstable system... IMO. The X58 boards have never been the best at having all six DIMM slots full... IMO.