Testbed configuration
Since the primary target platform for the
above discussed memory kits is Ivy Bridge + Intel Z77, we will examine 32 GB
G.Skill kits containing four 8GB modules each in an LGA 1155 system built on Asus
P8Z77-V Deluxe mainboard. Because the overclocking memory modules reviewed today
are primarily purchased by enthusiasts, we also used Intel Core i5-3570K processor
overclocked to 4.5GHz.
Intel
Core i5-3570K processor
As a result, the complete list of hardware
and software components in our test bed looked as follows:
·
CPU: Core i5-3570X, overclocked to 4.5 GHz (Ivy
Bridge, 4 cores, 6 MB L3);
·
CPU cooler: NZXT Havik 140
·
Mainboard: ASUS P8Z77-V Deluxe (LGA 1155, Intel
Z77 Express)
·
Memory: G.Skill Ares F3-1333C9Q-32GAO (4 x 8 GB,
DDR3-1333, 9-9-9-24); G.Skill RipjawsX F3-1600C9Q-32GXM (4 x 8 GB,
DDR3-1600, 9-9-9-24); G.Skill Sniper F3-1866C10Q-32GSR (4 x 8 GB,
DDR3-1866, 10-11-10-30); G.Skill RipjawsZ F3-2133C9Q-32GZH (4 x 8 GB,
DDR3-2133, 9-11-11-31); G.Skill TridentX F3-2400C10Q-32GTX (4 x 8 GB,
DDR3-2400, 10-12-12-31)
·
Graphics card: Nvidia GeForce GTX 680 (2 GB /
256 bit GDDR5, 1006/6008 MHz);
·
Drive: Intel SSD 520 240 GB
(SSDSC2CW240A3K5)
·
Power supply unit: Corsair AX760i (80 Plus Platinum,
760 W)
·
Operating system: Microsoft Windows 7 SP1
Ultimate x64
·
Drivers: Intel Chipset Driver 9.3.0.1026; Intel
Management Engine Driver 8.1.2.1318; Intel Rapid Storage Technology
11.7.0.1013; NVIDIA GeForce 314.09 Driver
Configurations with 4x8GB Memory Kits: Closer Look
Before getting down to testing the memory
kits described above, we wish to emphasize general problems of using dual-channel
memory kits containing four 8GB modules. Although we mentioned above that the
Ivy Bridge memory controller could easily support such configurations, there
are some nuances you should be aware of.
First, not all operating systems are ready
to support 32 gigabytes of system memory. Of course, you need a 64-bit OS
because 32-bit ones cannot access more than 4 gigabytes of address space. In
addition, each 64-bit Windows version has specific limitations. For example,
Windows 7 Home Premium only supports 16 GB while Windows 7 Home Basic, 8 GB.
Windows 8 has no such limitations, supporting at least 128 GB of system memory
in each version.
Second, it’s not correct to say that Ivy
Bridge CPUs are indifferent to whether you have four or two memory modules. Clocking
the memory bus at high frequencies may require your lowering the Command Rate
parameter. Therefore, if the mainboard has only two DIMM slots filled in, the
memory subsystem nearly can always work at Command Rate = 1T. With four modules
installed, you can only select 1T at speeds up to DDR3-2000 inclusive. Faster
memory configurations will require Command Rate = 2T.
Ivy
Bridge CPUs
Still, the Command Rate parameter is not so
important. It can often be ignored completely. Describing the latency between
receiving and decoding the addresses and instructions, it helps eliminate potential
access errors at high loads on the memory controller. Its impact on memory
performance is very low. Comparing two memory configurations - two modules with
Command Rate 1T and four modules with Command Rate 2T - we can see the second
one to be even faster as it contains more memory banks.
It is easy to illustrate with tests that we
conducted using the 32GB DDR3-2133 SDRAM kit RipjawsZ F3-2133C9Q-32GZH. First,
we ran it at its default timings of 9-11-11-31-2T and then we only got two
modules and improved the timings to 9-11-11-31-1T. Here are the results:
Test
result conducted by using the RipjawsZ F3-2133C9Q-32GZH
As you can see, the two configurations are
quite close to each other in performance. Therefore, there is no reason to
worry about having to set the Command Rate = 2T with four memory modules. The internal
organization of the four-piece memory subsystem compensates for that.
However, another peculiarity of four-piece 32GB
memory kits is that they create a lot of heat. We used to say that radiators
for DDR3 modules are largely just a decorative element, but actually, they are
necessary for overclocker-friendly kits made of four 8GB modules. Such modules
have a lot of chips and are placed close to each other on the mainboard, limiting
the natural convection of air. As a result, the temperature may rise rapidly.
Therefore, it's good to have radiators, especially with advanced finning, on
such memory modules.
However, the radiators must not be too
high. When you fill in all of the mainboard’s memory slots, the one nearest to
the CPU socket will be covered by the CPU cooler. Therefore, the latter should
be able to hang above the memory modules without pressing against their radiators.
The list of compatible CPU coolers shrinks significantly when the memory
modules have a total height of 40 mm.
