I am not sure what you mean by its just a 400 mhz OC.. Are you talking about my CPU OC? That is an 800mhz over clock from 3.4 to 4.2 ghz. My memory I havent touched and its at 1600 mhz 8-8-8-24. My board is the Asus p8z77 v pro. I probably should have mentioned that.... My only concern is that I will have to tweak things. I absolutly do not want to that is why i opted for replacing instead of adding 2 more sticks. Also replacing them would let me replace the 1600 mhz with 2133 mhz instead.
No -- not the spread between the base clock and OC'd turbo-clock, but the difference between stock turbo and OC turbo. About 400 Mhz.
My earlier-gen SB-K is OC'd 800 Mhz above the original turbo clock. I'm pushing the CPU to just below the expected stable maximum. You have more headroom than that, I'm sure of it. Somebody tell me if I'm wrong.
I see where some people were trying to clock the 3570K to 4.8, which is a bit ambitious. Another person had his set to 4.5 with voltage at 1.3V. The processor is safely capable of volting at 1.32V, as I recall. It's a 22 nm processor; mine is a 32 nm and the accepted voltage limit for sissies like me is ~ 1.37V.
You're not pushing the wall at all running at 4.2. Of course, the maximum depends depends on what cooling you now have, but if it's rock stable at 4.2 (which should be easier than eating Gerber's baby-food from the bottle) -- no -- I'm pretty sure you wouldn't have to tweak anything for the second RAM kit. Especially not for running DDR3-1600's.
It seemed to me that 4.2 had been the target for OC'ing with the VCORE set to "auto" -- or anything deficit would require a minimum extra. How did you come to overclock it? Did someone else do it?
From your remarks, it's stable. If you used the "AI overclocking" features, it could actually be over-volted or beyond what's necessary.
You have a good motherboard. I'm very optimistic about buying the kit, popping them in, firing it up to a self-booting memory diagnostic like HCI Memtest 64, passing 300% if you don't get a bad kit, and moving on without a problem on this. I don't think I've ever had a G.SKILL kit that had a defect when I bought it, and anything that went south was the result of a bad PSU. But I always test the RAM thoroughly when I install it in case so that I can turn it around with the reseller right away. And G.SKILL is very good with their lifetime warranty and turnaround time.
JUST ANOTHER REMARK: IF you want to spend the extra cash on a 2x8GB kit, that's the sort of thing I might do -- or have done. Ultimately it should hardly matter -- my best guess -- except you'll be less likely to run at Command-Rate =1 with 4x4, and more likely with 2x8. And maybe you can -- but the difference is marginal. That would also allow you to get a faster kit. Or -- you could get the second 2x4, loosen the timings to maybe 10-10-10-30, and run all four sticks at 1866.
There are a lot of possibilities, and what is more convenient for you, simpler, and not outrageously costly -- more than one way to skin that cat.
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