It really shouldn't work. Ram is picky about who it plays with, main reason ram is sold in kits. Your ram there have different latency speeds which doesn't work well. If you do feel obliged to try to mix and match ram (not really suggested) ensure all speeds and voltages are identical.
See what your system is reporting as ram, if it is recognizing what you have currently installed. If all your ram is recognized in BIOS, set the latency speeds to 9-9-9-24 (if it hasn't been done automatic).
Cool, weird, but cool.