Patriot Memory Viper Xtreme Division 4 16GB (4x4GB) PC-1500 1866MHz RAM Kit Review - Test Setup and Overclocking
CPU: Intel i7-3930K @ 3.8GHz
CPU Cooling: Arctic Freezer i30
Motherboard: ASUS P9X79 Deluxe
RAM: 4x4GB Patriot Viper Xtreme Division 4 1333MHz DDR3
GPU: ASUS GTX 560Ti 448 Core @860/950 MHz
OS HDD: OCZ Vertex 3 120GB MaxIOPS
Secondary HDD: Patriot Pyro SE 60GB
OS: Windows 7 Professional 64-Bit
Our testing methods will be fairly simple. We're first going to test the RAM at default settings, what you'd get if you didn't touch a thing after installing the sticks, which yields a 1333MHz default at 9-9-9-24 timings. Then, we'll enable the default X.M.P. profile, which for our kit, will bump up the kit speeds quite a bit to 1866MHz and 9-11-9-27 timings. This default value could also be 1600MHz or 2133MHz, depending on the kit you buy. Our third and final test point will be overclocked to 2133MHz.
We will be holding the CPU frequency constant at 3.8GHz, disabling SpeedStep, Turbo Boost, and the power-saving features on the i7-3930K, as the speed of the memory is directly tied to the processor frequency. With all three settings, the voltage settings for the processor and memory were left as an "AUTO" setting. We'll then run several synthetics to gauge the performance of the memory, including AIDA64, SiSoft Sandra, and PCMark 7.
When trying to overclock to 2133MHz, we found that the limiting factor was a single out of the four that held us back a bit. Using ASUS' slick SPD Tool on the motherboard, we were able to obtain special DIMM reporting which showed that one of the sticks showed as "Abnormal" when simply bumping up to 2133MHz operation. The other three were reading properly without any voltage or timing changes.
Bumping up to 2133MHz wasn't too difficult, we had to bump the timings back to 10-11-10-30 from the default 9-11-9-27, to get the single incooperative DIMM to operate stably. This is a pretty impressive result, and will give you a nice boost over the default 1866Mhz, but by reducing the timings, the gains are somewhat offset.
This is a good segway for us to a quick comment on memory performance, and how timings and clock speeds interact to provide memory performance. Think of it a race, where one racer is twice as fast as the other. The slower one gets to go first (lower latency, less wait time) but runs less fast. The faster runner (higher clock speed), has to wait twice as long to start running (twice as high latency) but catches up with greater speed (higher clock). Now lets, for simplicity's sake, assume they arrive at the hypothetical finish line at the same time, both racers have the same relative speed. So with this analogy we can see that overall RAM speed isn't remarkably simple, and is a "tango" between clock speed and latency. Generally speaking, the faster runner will finish first, but often to increase that speed, he must take longer "rests," which somewhat offsets his gains. This is what we see by the diminishing return in memory overclocking.