How would you like a car engine that can go 250 miles per hour? There's just one problem: the tires can't go faster than 140 miles per hour and there's a 65-mph speed limit. Similarly, today's extreme data-rate memory brings RAM up to DDR4-4600 speeds, but few motherboards and CPUs support it. According to some of our tests, this kind of high-speed RAM may actually perform better when lowered to DDR4-4000 speeds.
With its XPG Z1 DDR-4600 RAM, Adata is the third brand to release 4600-capable RAM. And though these DIMMs promise industry-leading performance, we found that competitors with lower maximum speeds outpaced them.
We received two of Adata’s AX4U460038G19-BRZ1 modules which, when sold in pairs, gets the AX4U460038G19-DRZ1 model name. The dual-channel kit includes two 8GB DDR4-4600 modules rated at 19-23-23-46 timings, beating the 19-26-26-46 ratings of the previously-mentioned Corsair kit.
These boot at DDR4-2666 before enabling XMP, and that’s as good as it gets for boards that don’t support XMP, unless you’re expert at manually configuring memory. Enabling XMP on compatible boards brings these modules up to their rated settings at an incredibly-high 1.50V, far exceeding the 1.35V limit after which Intel says that CPU longevity could be an issue.
Overclockers figured out long ago that if they wanted to exceed Intel’s limit without damaging the CPU, they only needed to increase the voltage of its memory controller to keep the difference between high (DRAM signal) and low (memory controller) within the 300mV threshold allowed by Intel. Boards listed as being DDR4-4600 capable are designed to do that automatically, with our MSI board increasing “VCCSA” and “VCCIO” to 1.40V from its 1.15V and 1.10V defaults, respectively.
Adata DRAM is covered by its lifetime limited warranty.
Test & Comparison Hardware
We’re comparing three of our fastest kits to Adata’s XPG Z1 DDR4-4600 using MSI’s Z370i Gaming Pro Carbon AC and the hardware from its review. Overclocked to 4.80 GHz, Intel’s Core i7-8700K works with MSI GTX 1080 Toshiba/OCZ RD400 SSD to minimize other system bottlenecks.
Our fastest kits include Corsair’s Vengeance LPX DDR4-4600, G.Skill’s Trident Z DDR4-3866, and Super Talent’s Project X DDR4-3733. Supply of the later set is limited and last seen at $260, which hardly seems a pricing issue since the widely-available G.Skill kit is currently priced only $10 higher.
Each of the module sets in today’s review was capable of at least DDR4-4000, so we turned them up (or down) and then sought out the lowest stable latency settings. Since latency is measured in cycles and clock rates are the inverse of time (nanoseconds), DDR4-4000 CAS 20 has the same response time as DDR4-3600 CAS 16.
|Lowest Stable Timings at 1.35V (Max) on MSI Z370I Gaming Pro Carbon AC (BIOS 1.30)|
|Adata XPG Z1 16GB AX4U460038G19-DRZ1||18-18-18-36 (2T)||14-14-14-28 (2T)||11-11-11-28 (2T)|
|Corsair Vengeance LPX CMK16GX4M2F4600C19||18-18-18-36 (2T)||14-14-14-28 (2T)||11-11-11-28 (1T)|
|G.Skill Trident Z 16GB F4-3866C18D-16GTZ||18-18-18-36 (2T)||14-14-14-28 (2T)||11-11-11-28 (1T)|
|Super Talent Project X F3733UX16G||19-19-19-38 (2T)||14-14-14-28 (1T)||11-12-12-28 (1T)|
Even though both DDR4-4600 kits are rated at 1.50V, we stuck with Intel’s stated DRAM voltage limit (1.35V) when attempting to overclock. Doing this allows today’s overclocking results to be compared to those of our other reviews. While the XPG-Z1 barely outpaced its more-expensive Corsair rival, the cheaper G.Skill and Super Talent kits followed closely.
The biggest tuning problem we found in the XPG Z1 DDR4-4600 was its inability to support a 1T Command Rate at DDR4-2400. The following benchmarks help to illustrate how that affects performance:
Boosted by its tighter primary timings at full XMP data rate, the XPG Z1 was surprisingly faster than the Vengeance LPX. Then again, the Vengeance LPX’s XMP timings were so loose that it showed better performance with its timings manually optimized for a lower DDR4-4000 data rate.
We picked one game and one CPU-intense application to illustrate best and average performance scenarios. F1 2015 and 7-Zip have extraordinary reliance on DRAM performance, yet both show performance to be inversely proportional to data rate. The likely cause for this is tighter sub-timings for the “slower” kits.
Metro and Blender tend to scale back only when memory timings or data rates are extremely bad, such as the poor score for Metro at the XPG-Z1’s 2T Command Rate at DDR4-2400.
Now that Adata sells through Amazon, you can expect a few of its DDR4-4600 kits to pop up there at Adata’s $450 MSRP. Eventually. Until they do, we’d be hard pressed to recommend them.
Looking at the value chart, we’d be hard-pressed to recommend anything faster than the G.Skill Trident Z DDR4-3866. We’d go a step farther and voice our preference for the Super Talent DDR4-3733 were it still widely available. If you want the bragging rights associated with RAM that has the highest data rate, Adata’s XPG Z1 DDR4-4600 is both better-performing and cheaper than Corsair’s Vengeance LPX. However, we don't recommend getting any DDR-4600 RAM at this time.
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