As we shown in our special review of the memory controller in modern LGA1155 CPUs, it is the operating frequency of dual-channel memory kits that has the biggest effect on the platform's performance. Therefore, increasing it above standard levels is the key feature of overclocker-friendly memory kits that helps ensure an additional performance boost.
The G.Skill memory kits are promising in terms of overclocking potential. Even though they include twice the normal number of DDR3 SDRAM modules, they feature efficient cooling and high-quality chips. G.Skill is also known to endow its products with a large safety margin. All of this gives us hope that these modules can work at higher clock rates than specified officially and may prove that there's nothing wrong about using a 4-piece memory kit on a platform with a dual-channel memory controller.
Here’s our algorithm of testing the overclocking potential of DDR3 SDRAM:
- Memory voltage is increased to 1.65 volts which, according to Intel, is the maximum value that doesn’t lead to degradation in the memory controller’s performance. We also increase the VCCSA voltage to 1.0 volts, which should theoretically have a positive effect on the memory controller’s stability;
- Failsafe timings of 11-13-13-31-2N are selected to find out the highest frequency the memory kit is stable at;
- Using the maximum frequency we’ve found, we then look for the most aggressive timings at which the memory kit is still stable.
The stability of the memory subsystem is verified by 10 runs of LinX 0.6.4 AVX Edition using the whole memory amount and by an additional 1-hour-long check with Memtest86+ v4.20.
G.Skill Ares F3-1333C9Q-32GAO
The simplest of our 32GB memory kits from G.Skill isn’t so bad at overclocking. Well, with the current level of technology, it is rather hard to make DDR3-1333 SDRAM chips incapable of working at higher frequencies. The Ares F3-1333C9Q-32GAO can actually be used not only as DDR3-1600 but also as DDR3-1866.
We had to relax the timings and increase the voltage to 1.65 volts to make them stable at 1866 MHz, so the Ares F3-1333C9Q-32GAO kit should indeed be viewed as an inexpensive solution for when you need a large amount of system memory.
G.Skill RipjawsX F3-1600C9Q-32GXM
Besides the beautiful color of their heatsinks, the RipjawsX F3-1600C9Q-32GXM modules can distinguish themselves with their overclocking potential. After increasing their voltage to 1.65 volts, we managed to achieve stability in DDR3-2133 mode. That's what we can expect from the Micron chips which are so popular among enthusiasts.
The lowest timings the RipjawsX F3-1600C9Q-32GXM kit was stable at in DDR3-2133 mode were 11-12-12-33. You can also note that we had to switch the Command Rate parameter to 2T. Choosing a lower value for it caused memory errors at high loads.
G.Skill Sniper F3-1866C10Q-32GSR
Describing the Sniper series kit above, we noted that it is meant for gamers rather than for overclockers. Therefore, we were not surprised at its low overclocking potential. The Sniper F3-1866C10Q-32GSR kit is rated for DDR3-1866 and we could only raise the clock rate by 133 MHz even at a voltage of 1.65 volts.
On the other hand, this memory could work as DDR3-2000 with CL = 10, i.e. with its timings close to their defaults. The unnamed chips below the heatsinks of the Sniper F3-1866C10Q-32GSR modules seem to have been tested by G.Skill to be appropriate for the product’s market positioning.
G.Skill RipjawsZ F3-2133C9Q-32GZH
High-speed memory kits for computer enthusiasts can but rarely show high overclocking potential because they already make the most of the employed chips. It is even more difficult with 4-piece memory kits just because they include more memory devices. It is quite an achievement that our DDR3-2133 kit RipjawsZ F3-2133C9Q-32GZH was stable at 2200 MHz in our tests.
Moreover, we could even improve its timings. The default timings are 9-11-11-31 but our RipjawsZ F3-2133C9Q-32GZH kit could work at 9-10-11-31 at the increased clock rate.
We can also note that we’ve tested a number of memory products from different brands with SEC HCH9 chips. Like the RipjawsZ F3-2133C9Q-32GZH, such modules can usually be overclocked to 2200-2600 MHz, so the G.Skill product is quite a typical representative of its class.
G.Skill TridentX F3-2400C10Q-32GTX
The fastest 32GB memory kit in this review is rated for 2400 MHz. It must be noted that G.Skill has recently announced DDR3-2800 kits, but doesn’t yet really offer them at the time of our writing this. This might give us some hope that the TridentX F3-2400C10Q-32GTX could be overclocked a little, but that’s not so. Our sample of this memory kit wouldn’t work even at 2600 MHz.
So, there was no overclocking actually. We could only lower RAS# to CAS# Delay a little, dropping the timings to 10-11-12-31. Overall, the TridentX F3-2400C10Q-32GTX has zero overclocking potential but that’s no downside. It is just a characteristic feature of any memory modules which are rated for high frequencies. Their memory chips are already overclocked to the limit without our intervention.
The results of our overclocking experiments are summed up in the following table:
Apart from the Ares F3-1333C9Q-32GAO kit which has low official specs, the memory kits from G.Skill are similar in their overclocking potential. All of them can be overclocked to above 2 GHz, i.e. to speeds which are most popular among enthusiasts. Of course, memory rated for a lower default frequency has better relative overclocking potential. The high-speed modules do not overclock well but feature SEC HCH9 chips that enjoy an excellent reputation among overclockers.