I have 4 ddr3 ram slots at different mhzs 16 gigs

I wouldn't try it....Windows 7/8 will give you the BSOD quite often...it would be unstable.

With the speed and sensitivity of today's CPU, mobo and RAM, it is unwise to even install RAM that isn't from the same manufacturer's run. I personally only buy a full kit to install in a PC - never mix them. An example would be if I wanted 16GB RAM, I would be a kit of 4 X 4GB or 2 X 8GB in one package.

Mixing frequencies can very well cause stability problems. Especially at high clock speeds. Buying it from a kit is not really necessary as long as all the specs (freq/size/voltage/density) match.

There should be no problem them.

If you mix DIMMs with different frequencies and timings, you have to use the slowest clock and slowest latency timing of the modules you are mixing to maximize your chances of getting something that works.

Ex.: if you are mixxing 1866-10-10-10 with 1600-9-9-9, your best shot would be something like 1600-10-10-10. If this does not work, you can try 1333-10-10-10. If this still does not work, you are likely out of luck.