Patriot PX416G240C5K Review

The time has now come for us to perform our usual overclock-testing of the test sample. Even if you are not planning to overclock your memory, knowing its spec headroom and overclocking capabilities can serve as a good assessment of manufacturer's quality control.

We conduct our experiments using a test platform based on Intel's latest generation of CPUs, which is commonly known as Skylake.

 CPU  Intel Core i7-6700K (running at 4.5 GHz)
 Motherboard  MSI Z170A Gaming M7 (BIOS version 1.85)
 Memory  Patriot Viper Xtreme PX416G240C5K
 Graphics card  ASUS HD4350
 Storage  Kingston SSDNow V300 60GB
 Power supply  Seasonic Platinum 1200W
 Operating System  Windows 7 SP1, 64-bit

There are many ways to test stability of the system but our method of choice is HCI Memtest as it is the toughest memory stresstest that we are aware of. As we are dealing with a 16GB kit on a CPU that can handle 8-threaded load, we use eight 1600MB instances and call things stable if we see all of them run past 150% without showing a single error. Each pass of such a test takes about one hour to complete.

Our test platform has a very wide range of memory clockspeeds to choose from, but to keep things simple we will only concentrate on DDR4-2800, -3000, -3200 and higher modes leaving the intermediate options out as potentially irrelevant. Once we select the memory frequency, we seek for optimal combinations of primary timings, for which we minimise the stable voltage in 0.01V increments.

When overclocking Hynix-based memory modules we usually observe the following behavior. If the CAS latency is kept without change, then the dependency between stable frequency and minimal stable voltage is close to linear. What comes to the rest of primary timings (tRCD, tRP and tRAS): the minimal stable values depend primarily on the memory frequency with voltage playing a secondary role in the borderline areas. However, on Skylake you also have to keep in mind that tRCD must be equal to tRP at all times and that the minimal tRAS value one can set in the BIOS is 28.

Below you can see the list of stable configurations that we were able to achieve with our sample.

1400MHz (DDR4-2800)
1500MHz (DDR4-3000)
1600MHz (DDR4-3200)
  CL11
not possible
not possible
not possible
 CL12
12-14-14-28 @ 1.56V
not possible
not possible
 CL13
13-14-14-28 @ 1.42V
not possible
not possible
 CL14
14-14-14-28 @ 1.32V
not possible
not possible
 CL15
15-14-14-28 @ 1.26V
not possible
not possible
 CL16
16-15-15-28 @ 1.22V
not possible
not possible

Obviously, with a spec as low as 1200MHz CL15, it is near impossible to find fully functional memory chips that would fail to clear it. Because of this, we moved on straight to higher clockspeeds.

Getting our test sample to run DDR4-2800 was extremely easy, it could even lower the timings to 12-14-14 given enough voltage. However, DDR4-3000 and anything above was mission impossible. Irrespective of the timings, subtimings, voltages and platform-related settings, we would occasionally have Memtest errors around the 70% mark, which would cross the DDR4-3000 mode out as potentially unreliable. This makes Patriot kits two for two on unexplained overclockability issues, so there is clearly something wrong with chip binning within the company.

To see the practical gain of overclocking the memory, we made a quick performance comparison using AIDA64 Cache&Memory test, CineBench R15 and XTU between the XMP and our best overclock. Note that with the latter we have slightly optimised the secondary timings and you can also use our values as a starting reference.

PX416G240C5K_performanceDEF PX416G240C5K_performance1400c12

According to AIDA64, a memory overclock has improved our memory bandwidth by more than 15%. If XTU is to be trusted, it has boosted the Prime95-based performance of our setup by around 9%. However, a more realistic Cinebench score went up by just 1 percent.

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