Any publication that’s still claiming that high-end PC “gaming” hardware is driven by necessity is probably one you shouldn’t be taking too seriously. The numbers have been in for a while, and the truth is that DRAM kits such as these aren’t useful for improving your gaming performance. These kits exist purely to push the envelope insofar as PC component technology is concerned.
DDR4, much like all previous iterations of the specification, was never meant to achieve these frequencies, as it was initially spec’d from DDR4 1,600 to 3,200MT/s. That we managed to reach 4GHz and above in a mere three years is quite remarkable. With kits such as these, we’ve gone beyond 1GHz higher than the initially projected frequencies.
That said, the pursuit of ever-faster, better-performing memory is something that resonates with me and I’m sure many others like me who have a somewhat keen interest in PC DIY will feel the same. We’re well aware that such memory kits are overpriced, do nothing for gaming performance and generally have no meaningful application for the vast majority of users and enthusiasts. Nevertheless, this is a great RAM kit and one well worth owning if you’re an enthusiast and have the spare change.
DRAM prices are set to skyrocket for a number of reasons, and kits such as this won’t be getting any cheaper. While there’s currently no local pricing for the memory, don’t expect it to come in at anything less than R6,999 – which is an insane amount of money to pay for 16GB of memory. If that price doesn’t bother you, then you may be in for one of the finest memory kits Corsair has ever produced. Granted, this kit isn’t of the much-vaunted Dominator Platinum family, but it holds its own where it matters most.
Rated at 4,333MHz, not many systems will be able to use this memory. Their use is likely limited to the Z370 platform, as there isn’t a readily available Z270 (let alone Z170) motherboard that could support the desired memory divider. Even on the recent X299 platform, these frequencies are simply unattainable. Fortunately, if you’re planning on buying any of the two DIMM performance-oriented boards, you’re in luck. I tested this kit on one of those motherboards, the ASUS ROG MAXIMUS X APEX, which we may review at a later date.
Frequency alone doesn’t tell you much, but those of you familiar with how DRAM works at even a superficial level are aware that higher timings generally mean diminished performance. That isn’t how DRAM functions though, as the increased frequency results in reduced clock cycle times. Depending on the ICs used, what usually happens, for instance, is that DDR4 3,000 C14 finds itself pitted against DDR4 3,200 C16. The clock cycle time is often insufficiently reduced by the increase in frequency to offset the increased CAS latency.
As these are the most frequently represented comparisons (via memory roundups and the like), we’re left believing that this holds true always – even in situations where it doesn’t. We come to the right conclusion in practice, but for all the wrong reasons. In reality, it’s finding the right balance between timings and frequency which gives the best performance.
With this memory, Corsair has been conservative to say the least, specifying 19-26-26-46 as the primary XMP timings. The headroom given for varying IMCs inside CPUs is rather large, and more aggressive timings could’ve easily been used. It’s understandable to some extent, as the vendor specifications must account for a wide range of systems. The higher the tolerance levels, the fewer support calls and RMA requests. Basically, vendors (or at least ones that move large volumes of memory) try to eliminate the headache and lost revenue that comes with support queries related to high-speed DRAM kits.
Even with that in mind, Corsair could’ve easily set the timings to 19-23-23-46 without issue. The reason I can say this with some certainty is because this very kit was not only able to pass in Hyper PI 32M (which is still useful as a memory stress test for CPUs with 16 or fewer threads) and MemTest with 100% stability, but it did so at less than the specified voltage. This kit has a 1.4V operating voltage, but I managed tighter timings at the same frequency while using a lower voltage of 1.35V.
All that aside, the important questions are: how far can this memory be pushed, and what kind of performance should I expect? Well, that’s all laid out in the benchmark results. Out the box, this memory is impressively fast, and if you left it at default after loading XMP you’d be getting a lot more performance than you would from just about any other memory kit you can buy right now.
The real fun is in the tuning, however, and in the many hours you could spend toying with it. It’s safe to say that the real limit to what’s possible is still largely the CPU and the mainboard. As fantastic a board as the APEX is and as refined an IMC as the Core i7 8700K has, this memory is still capable of more – and this is easily observable by the mere fact that anything above 4,550MHz or so has trouble passing POST. It’s similar behaviour to the Z270 platform, where no memory ratios above 4,133MHz worked and the same kit was limited to around 4,200MHz. In fact, when tested on the MAXIMUS IX APEX, the limit for this memory was around 4,266MHz using BCLK adjustments.
That said, 4,533MHz is a scorching frequency, higher than what many K SKU CPUs operate at. Remember that 4,533MHz will still need some tuning though. At the very least, you’d have to adjust the primary settings manually in order to prevent the motherboard from setting even more relaxed timings, which would negate any performance gains you’d make via the increased frequency.
In testing it became rather obvious that finding the sweet-spot is entirely dependent on the system. What I can say is that attempting tight competitive overclocking timings at low frequencies is not an optimal strategy. If you’ve got a motherboard which can attain the super-high frequencies, then definitely stick to 4,000MHz and at a bare minimum of 3,600MHz. In each case, you should be able to tighten the primary memory settings to 14-14-14-32 using a 1N/1T command rate. If for whatever reason that isn’t possible, you simply don’t have the right motherboard to match with any form of high-performance memory. Given that this memory likely costs more than the motherboard itself, make doubly sure that your motherboard is capable of handling it.
As you can see in the benchmarks, the sweet-spot for this memory is at 4,000MHz – or 4,533MHz if you can manage it, as it’s close in performance. Be aware that running such a high DRAM frequency means the board will set an unusually high VCCIO and perhaps VSA voltage. For the uninitiated, these two voltages are responsible for cache and memory subsystem stability and operation. Since these terminate within the CPU, they can cause CPU temperatures to rise. In this particular case, when using XMP settings the standard VCCIO voltage was 1.4V and VSA between 1.35V and 1.38V, compared that to the standard ~1.108V and ~1.0V you’d typically find at 3,200MHz. A side effect of high memory frequencies isn’t just the heat generated by the memory, but more importantly the additional stress it places on the CPU, if only via the increased temperatures under load.
Fortunately, these are the standard “AUTO” detection rules as applied by the motherboard and they can be lowered somewhat. In this case, 1.35V VCCIO and 1.3V VSA did the trick and helped the CPU shave a couple of degrees off the top.
While there’s not much anyone can do about the heat generated from the CPU, you can do something about the heat coming off the DIMMs. Corsair includes the Vengeance Airflow fan solution (not pictured), which’ll certainly keep the DRAM and surrounding ICs cool. If you’re going to operate the memory at 4,333MHz with optimised timings (and especially if you’re going to attempt 4,533MHz), I’d definitely suggest using the supplied cooling kit.
There’s really not much to dislike about this kit. It’s not meant to be practical or cost-effective. It’s simply Corsair pushing the limits of current DRAM manufacturing, and relying on their sorting and testing abilities to bring such a high-performance kit to the PC DIY market. There’s no need for anyone to try to sell you on the kit as anything but what it is. It’s simply a masterful display of technical knowhow and affords you the luxury of living at the cutting-edge of technology.
Only high-end gamers and pure performance enthusiasts need apply. Corsair’s Vengeance LPX DDR4 kit is mighty fast and highly capable beyond what current platforms allow. It’s impressive to say the least.