Welcome, Newcomer. Generally it is always recommended to buy your RAM in kits, this ensures compatability within the kit. This is especially true when building a new system. However, mixing RAM can be done.
What you want to focus first is the voltage. 1.5 and 1.65 is a pretty large gap, in terms of RAM voltage. Your CL9 stick(s) recommend 1.5V to use their specified timing. This may pose a problem for you because your CL8 stick(s) recommend 1.65V. The problem is that if the CL9 can't operate at 1.65V, you'll have to try to get the CL8 sticks to operate at 1.5V, or somewhere in between where the two happily agree on.
The next thing you'll need to work on is the timing. Start by manually configuring your BIOS to 9-9-9-24. Then F10 to save and exit. Load Windows and monitor for stability. To aid in this venture, download and install Prime95. This software will put 100% load on your CPU while testing your RAM simulatenously. Note that this test is for stability, not to determine where (if any) errors in your RAM are.