Memory Performance Results

Test System

Testing Rated Speeds

I have recently built a new system for memory testing, and I spent about 8 weeks playing with multiple Haswell CPUs and multiple Z87-based motherboards before settling on the configuration used for all testing. Due to memory overclocking in part being limited by CPU speeds, I have chosen to run all testing with my Intel Core i7-4770K running at default speeds, although I enabled ASUS's performance-optimized turbo profiling feature. All kits are tested by simply enabling XMP in the BIOS after clearing the CMOS fully. I also clear the CMOS when I swap kits to ensure that the reported numbers are identical to what end users can obtain using a similar configuration.


Booting the G.Skill F3-2133C9Q-16GXL kit up in the ASUS MAXIMUS VI EXTREME worked perfectly, although I noticed that the ASUS board used its own secondary timings instead of what is listed in the in-BIOS "SPD Tool". The timings used by the board are part of the ASUS MemTweakIt screenshot above. There are two XMP profiles in BIOS, and I asked G.SKill why that was, and it was explained that the XMP v1.3 profile is for Haswell-based systems, while the other is for earlier systems, which makes the voltage used on my Haswell-based ASUS MAXIMUS VI EXTREME 1.60 V. Older systems will use the other XMP profile and its slight boost to 1.65 V.

Maximum Overclock

I tried overclocking these sticks in many different ways, with the BCLK at 125 MHz and 166 MHz. To use different dividers, I tried various pre-set profiles in the ASUS MAXIMUS VI EXTREME BIOS, setting timings manually, increasing the voltage, and so on, but all without much success. Then it occurred to me that when I first ran the sticks, the ASUS BIOS used different timings than those in the "SPD Tool", so I manually set those timings and scaled the BCLK up from 100 MHz. With default timings and the voltage set to 1.65 V, I reached slightly over 2250 MHz stable. I tried loosening timings to push further, as the immediately obvious answer would be to set CAS 10 or CAS 11, and maybe adjust a few other things, or even boost the voltage, but that didn't work. So there does seem to be a BIOS issue with these sticks and this board, since these sticks have just been released. I also tried lowering the voltage, but that didn't prove helpful either, so I moved on and looked at the performance results instead.