First thing you should be aware of is that the pair from Newegg has CL10 vs your CL9 kit. If you were to put these two kits together, you'd have set the BIOS to run your RAM at CL10.
The second problem is the pair from Newegg operates at 1.5v, but your current pair needs 1.65v. This could be a problem for the pair from Newegg. You would have to set your DRAM voltage to ~1.66, because often times, using four (or more) DIMMs requires additional voltage for stability. Doing this may fry the pair from Newegg.
The above scenarios also takes into assumption that you actually successfully boot with the two mixed kits. A lot of times when RAM is mixed, systems will not have a display.