Hello,
 
I recently purchased a Z97 FTW to run an Intel i7 4790 (Haswell not Devil's canyon).  The board is doing fine, but I found I have a bad stick of RAM - one of the sticks gave me hundreds of thousands of errors running memtest86.  I bought Corsair Dominator Platinum 2x8gb DDR3 1600 Model CMD16GX3M2A1600C9, which was on the QVL for this board. I am going to request an RMA of my ram... but in the mean time, I'm writing to see if my OLD ram will run sufficiently well until the new replacement comes in.  
 
My old ram was Triple-Channel Corsair Dominator for a Core i7 960 build (on an EVGA x58 FTW board).  Corsair Dominator 3x4gb DDR3 1600 Model CMP12GX3M3A1600C9.  They ran like a clock in my old system, so I'm pretty sure the sticks are all OK.  I want to slap those in my machine until the replacement new ram arrives.

First: Will my machine run OK with the old ram installed?  It only has to stand like a 3 legged stool for a week or so until the replacement 8gb sticks come in.  
Second: If it will run at all, should I run it in 2x4GB for 8GB ram, or can I run all 3 sticks for 12GB of ram.  I'm not too familiar with this new board yet, so would it handle the 3 sticks OK?
 
Thanks for the help,
Chris

It should be the red slots, if I recall correctly.
 
Thanks for your help!

The memory should be fine, it is a bit higher voltage than the newer CPU's tend to like but if this is short term, and you are not clocking the RAM or anything it should be fine.  2 sticks should run in dual channel, 3 sticks will normally make the memory controller run at single channel.