Hmm, unless you set the timings manually on both set of RAMs, it should be OK. they're the same Manufacturer, and the same model, only different Cas Latencies
I'd recommend to set them at 9-9-9-24 on both sets.
Although it looks like the set you already have works at 1.65V, and the new will be working at 1.35V, somebody please correct me if i'm wrong, BUT! if you undervolt your current RAM to 1.35V and set the timings to 9-9-9-24 in the BIOS of course, would be totally compatible with the new set the OP wants to buy? :huh: