When I set the memory frequency at DDR3-1600, I see that the DRAM voltage which is set to AUTO shows 1.8 volts!! I never noticed it until today. All this time the computer is functioning without any trouble. But I remember talking to OCZ support the other day and he told me to set the voltage at 1.65V and timing at 8 8 8 24 (CAS-TRCD-TRP-TRAS). When I set the memory frequency at AUTO, it runs at DDR3-1067 and the voltages drop to 1.5V.
What's happening here, and why? and what should be my worry-free optimal settings if I want to run the memory at the highest possible speed? Would it affect my CPU cores' temperatures in any way?
The memory controller chip on the i7 runs at a default speed of 1067Mhz. and so if set on auto that is what the memory will be set to - also the default voltage spec for ddr3 is 1.5V so it will also default to that voltage. - In order to get it any higher the settings must be done manually!
And the LOW VOLTAGE tag is just a marketing gimmick to get people to buy those modules (since the early Intel MOBOs had problems with melting sockets if the voltage was set higher than 1.65 volts so many consumers are looking for low voltage in order to avoid this so will buy more modules that stick those 2 words in the spec !)
The memory controller on the i7 9xx chips runs at 1067 MHz by default. The i7 8xx chips will default to 1333 MHz. However, depending on how you loaded defaults in BIOS it may have set to a safer speed of 1067, or perhaps the info coded onto the RAM sticks caused the 1067 speed.
With an i7 8xx CPU you can run the RAM at 1600 MHz by changing the DRAM SPD (memory multiplier) to x12 (or some BIOS allow you to pick the speed directly). Yes you should also handkey the timings and set the V to 1.65V. That is the absolute max spec on the last couple Intel architectures. Anything higher than that can lead to problems, especially with the MCH on the Lynnfield (i5 7xx, i7 8xx) CPUs.
Or you could run them at 1333 and set the V to 1.5V and try to tighten the timings.