My 2008 Mac Pro 3.1 w/2x3.2Ghz now has 2x4GB kingston and 2x1GB (stock) for a total of 10GB. The next step is to buy 4x4GB (eBay-version with heatsink), and probably remove the two 1GB so I have a total of 6x4GB. Or also remove the old Kingston ones for 4x4GB similar ones. I'll probably never need more than 16GB on this machine anyways (Logic Pro/FCPX mostly). I think buying 2 kits for 32GB is a bit overkill when I could get up to 24GB with the 2x4GB Kingston modules I already have + the eBay kit. Could the 1GB ones stay in as well for 26GB?... My instinct tells me that Kingston/eBay (Micron or Samsung chips) mixed together won't be a problem at all. AFAIK the modules has to be installed in pairs, and I reckon that the best performance would happen if they all are the same (4GB) size modules. But after all, it's been running with the current setup for years and years. What are your opinions? My options are: - 16GB: 4x4GB eBay RAM - 24GB: 6x4GB (4x eBay RAM + 2x Kingston RAM) - 26GB: 6x4GB + 2x1GB (4x eBay RAM + 2x Kingston RAM + 2x "Apple" 1GB) (And 32GB, but that would involve buying 2x 16GB kits, which means $240 instead of $120 for the kits... And I probably don't need half of the RAM anyways) As i mentioned, I'm probably good with 16GB, but who can ever have enough RAM? The Kingstons (B1/2 memory modules) reach a temperature up to 80C on load, the other two are 60-70C max.