RAM with different frequencies?

[ProfCheops]

So when I built my pc I went with a pair of Corsair vengeance lp 2x4gb ddr3 DIMMs with a Freq. Of 2133Mhz

 

I now want to upgrade and to save money I want to just add 2 more DIMMs for 16gb. Although I found the same make (Corsair vengeance lp ddr3) although it's only 1600mhz. Will it work if I have half of my ram with 2133 and the other with 1600. Probably a stupid question but I want to know

[TheGlenlivet]

1 minute ago, ProfCheops said:

So when I built my pc I went with a pair of Corsair vengeance lp 2x4gb ddr3 DIMMs with a Freq. Of 2133Mhz

 

I now want to upgrade and to save money I want to just add 2 more DIMMs for 16gb. Although I found the same make (Corsair vengeance lp ddr3) although it's only 1600mhz. Will it work if I have half of my ram with 2133 and the other with 1600. Probably a stupid question but I want to know

It will all go down to 1600.  The Memory controller can't do different frequencies. 

If you NEED 16GB of Ram (for a specific application or something) then go ahead  If you don't NEED it, then you will actually make your system slower by installing the new 1600 MHZ dimms.

[it_dont_work]

Yes, but it'll most likely default to 1600mhz, or 1333mhz on both channels. I've hd good results over locking lpx most of the time, doesn't mean you can't just manually set the timings to say 1866 to start with

[ProfCheops]

I know about memory management decreasing the frequency to the lower DIMM but I've also read that there is the risk of the OS rejecting the new RAM due to this differing frequency. Is that risk high or is it negligible?

[TheGlenlivet]

Just now, ProfCheops said:

I know about memory management decreasing the frequency to the lower DIMM but I've also read that there is the risk of the OS rejecting the new RAM due to this differing frequency. Is that risk or is it negligible?

If both sets of DIMMS are on the approved RAM list of your motherboard you should be ok, but it is a risk.