Two different speed HyperX on Ryzen X370

So I had a kit of 2x4 GB HyperX CL14 2133 from a failed mining rig.
Built a new Ryzen system when the new chips released for a sweet deal on old parts.
Being it is going to be a jack of all trades server of sorts, I thought I better bump it to 16GB.
So I added a 2x4 GB HyperX CL15 2666. (Best deal at the time, so why go slower?)
Original BIOS would not post with the 2666 RAM. So for posterity sake, on a non posting Ryzen, try different RAM.
Anyways, sorry for the rambling, I got it to post with the 2133 RAM, then updated the BIOS, and now it see's all sticks for 16GB.
Sorry for the long-windiness, but my question is: What is my best option for OC'ing the RAM here.
Same brand, diff speeds. I have never attempted this before. I'm going for a mild OC, but honestly I have no concept of doing this with two different sets.
Any help is appreciated.

Ok. Start by downloading typhoonburner and find out what kind of chips you have. 2133 might be the best you can get with dissimilar chips and all the slots full. If they are similar you can try to get them to run at 2666 or 2400 with more voltage. Like 1.35volts to start.

Any luck? Was thinking you could sell the 2133 for cheap on the FS trade and pick up another set of 2666 to match with minmal cost after sale.

It was still on the test bench. When I get it into the case I will explore the options. Thanks for the reply's.
I will report back for posterity sake of other Ryzen users.