In my experience there are no decent short duration memory tests for large amounts of memory, unless one is simply looking for enough to get through a benchmark run without crashing.
Memtest86+ hasn't been updated with multi-threading yet, so is mostly worthless. The last few versions of vanilla Memtest86 are quite promising, as they are well threaded, but they are still buggy on some boards.
Hyper Pi/Super Pi really isn't that great of a test at all, even one instance per core isn't going to hit the memory hard enough, or use enough memory to be that useful.
LinX/IBT are okay, not great, as memory tests. However, when using problem sizes above 30k or so, they tend to slow down to the point they don't work memory as hard as they should. This limits the size of the memory you can reliably test with it. Still, it's a great processor and L3/IMC test at reasonable problem sizes.
Prime95 custom blend is still probably the best single test, though one should not rely on any one test exclusively.
HCI Memtest for Windows is also pretty good, if you run enough instances (at least one per logical CPU).