Strange issue, wonder if anybody has seen it before. Rebuilding an old i7 920 rig with an Asus P6TSE & 12GB RAM (6x 2GB Sticks). No overclocking etc as it's for an ESXi box for my lab. If I put my Dell Perc 6i card in to any of the PCI-e slots (so I can use my SAS drives) it reports as having 8GB RAM. If I remove it it shows 12GB RAM. Looks like it's actually taking out Channel B of the RAM when it's installed. Any ideas before I try another RAID card tomorrow?
I am pretty sure the issue is with some of the aditional CPU voltages, where the default voltage is not enough to drive all 6 memory sticks, while handling PCI-E interface as well. Try to bump the QPI/DRAM Core voltage a bit. S1366 CPU communicates with X58 (and with PCI-E devices through the chipset) using the QPI interface, and with memory using the memory controller - that is why there is a possibility that the default QPI/DRAM Core voltage is simply not enough and it drops one memory channel for correct functionality of the rest of the system.
