Another trip out to the shop today, another new set of RAM. These babies have looser timings but they have prettier heat spreaders. Hoorah! It took the good people at said shop 3 hours and 50 minutes to swap out said RAM. Unbelievable stuff. They also admitted to me, in Thai, that the entire shipment of GEIL RAM they bought recently is totally defective and they're trying to offload it as soon as possible. I don't quite know what to make of this tale. I ended up with Kingston HyperX.
Anyway, they've passed Memtest86+ a couple times and now it's just a case of re-installing Windows, re-downloading Civ V, and then finally, hopefully, getting my Civ on.
Thanks very much to all those who gave advice in this thread.
And be sure to stay tuned for the next episode.
Ubuntu 12.04 AMD64: E8200 // P35 // HD 4850 // 4GB
OS X 10.8.x: iMac12,2, MacBook 5,2