Overclocking

When it comes to memory overclocking, there are several ways to approach the issue.  Typically memory overclocking is rarely required - only those attempting to run benchmarks need worry about pushing the memory to its uppermost limits.  It also depends highly on the memory kits being used - memory is similar to processors in the fact that the ICs are binned to a rated speed.  The higher the bin, the better the speed - however if there is a demand for lower speed memory, then the higher bin parts may be declocked to increase supply of the lower clocked component.  Similarly, for the high end frequency kits, less than 1% of all ICs tested may actually hit the speed of the kit, hence the price for these kits increase exponentially.

With this in mind, there are several ways a user can approach overclocking memory.  The art of overclocking memory can be as complex or as simple as the user would like - typically the dark side of memory overclocking requires deep in-depth knowledge of how memory works at a fundamental level.  For the purposes of this review, we are taking overclocking in three different scenarios:

a) From XMP, adjust Command Rate from 2T to 1T
b) From XMP, increase Memory Speed strap (e.g. 1333 MHz -> 1400 -> 1600)
c) From XMP, test a range of sub-timings (e.g. 10-12-12 to 13-15-15 to 8-10-10) and find the best MHz theses are rated.

There is plenty of scope to overclock beyond this, such as adjusting voltages or the voltage of the memory controller – for the purposes of this test we raise the memory voltage to the ‘next stage’ above its rated voltage (1.35V to 1.5V, 1.5V to 1.65V, 1.65V to 1.72V).  As long as a user is confident with adjusting these settings, then there is a good chance that the results here will be surpassed.  There is also the fact that individual sticks of memory may perform better than the rest of the kit, or that one of the modules could be a complete dud and hold the rest of the kit back.  For the purpose of this review we are seeing if the memory out of the box, and the performance of the kit as a whole, will work faster at the rated voltage.

In order to ensure that the kit is stable at the new speed, we run the Linpack test within OCCT for five minutes as well as the PovRay benchmark.  This is a small but thorough test, and we understand that users may wish to stability test for longer to reassure themselves of a longer element of stability.  However for the purposes of throughput, a five minute test will catch immediate errors from the overclocking of the memory.

With this in mind, the kit performed as follows:

Test PovRay OCCT
XMP 1608.97 78C
XMP, 2T to 1T 1619.52 76C
2600 11-13-13 1622.18 77C
2666 11-13-13 1609.28 76C
2800 11-13-13 No Boot No Boot

Being able to adjust two memory strap options above XMP is actually very good showing.  Other kits tested in house have trouble doing one step, let alone two.

Subtimings Peak MHz PovRay OCCT Final PI
7-9-9 1600 1618.42 76C 229
8-10-10 1866 1601.58 77C 233
9-11-11 2133 1610.20 76C 237
10-12-12 2400 1589.52 77C 240
11-13-13 2666 1616.01 77C 242
12-14-14 2666 1620.62 77C 222
13-15-15 2800 1608.01 77C 215

A peak PI of 242 is a good result, showing that there is some headroom from the basic settings.

IGP Compute ADATA XPG V2 2x8GB DDR3-2400 C11 Conclusions
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  • Rick83 - Monday, November 11, 2013 - link

    So running memory on a 22nm CPU at 1.65 volts (or more, for the OC) has suddenly become acceptable again? Last I heard everyone clamoring to only get 1.5V memory, so as not to fry the IMC before its time.
    At $200, the key point is that by taking a $100 kit and putting those $100 dollars toward more memory or toward extra CPU performance would probably be better. Going with IB-E instead of with Haswell could probably done with that extra money - and you get double the memory channels to play with as a result.
  • IanCutress - Monday, November 11, 2013 - link

    Most DDR3 memory past 1866 C9 is at 1.65 volts. These IMCs are sturdy enough, almost all will take 2x8 GB 2933 C12 without breaking a sweat. When did it ever become unacceptable? I've never seen any issues except taking Sandy above 2400 MHz, because the IMC wasn't particularly built for it. Ivy kicked it up a notch and Haswell accepts most of what I throw at it as long as you're reasonable and the memory itself can handle it.
  • owan - Monday, November 11, 2013 - link

    There was a LOT of talk when SB released about using 1.5v ram instead of 1.65v due to the IMC supposedly not tolerating higher voltages well. I don't know how true it was, but I thought this was common knowledge.
  • hoboville - Monday, November 11, 2013 - link

    Yes, there has been (and still is concern) that over-volting RAM can have a negative impact on the memory controller, because it is on the CPU die. RAM voltages and power do have an impact on the memory controller, of that there is no doubt. In fact, Registered Memory (also known as Fully Buffered or just Buffered Memory) was a design that came about when the IMC had to interface with large amounts of RAM (and power), particularly servers where 8+ slots is not uncommon.

    http://en.wikipedia.org/wiki/Registered_memory
  • The Von Matrices - Monday, November 11, 2013 - link

    Well, according to Intel (http://www.intel.com/support/processors/sb/CS-0299...

    "Intel recommends using memory that adheres to the Jedec memory specification for DDR3 memory which is 1.5 volts, plus or minus 5%. Anything more than this voltage can damage the processor or significantly reduce the processor life span."

    However, I have not seen anyone who had a processor fail explicitly due to 1.65V memory. Granted, this might be hard to tell because many of the failed processors with 1.65V memory also have core overclocking and overvolting, and separating the actual cause of failure is impossible without an electron microscope.

    I run my Hawswell system at 1.65V DDR3-2400, and I am not worried about 1.65V killing the processor. What's more concerning to me is that my Mushkin Blackline memory's XMP profile adjusts the system agent voltage +0.3V, which is far too much for me. I forced it back to default voltage and the memory works fine.
  • jabber - Tuesday, November 12, 2013 - link

    It may be that Intel's research determined that running at 1.65v could reduce the life of the CPU from 30 years to 28 years.
  • freedom4556 - Tuesday, November 12, 2013 - link

    Yeah, I love that there is a huge difference between the statistical and colloquial meaning of the word "significant" that always seems to be abused by marketers and misused by media.
  • kishorshack - Monday, November 11, 2013 - link

    This is an Anandtech Review
  • hoboville - Monday, November 11, 2013 - link

    A quick suggestion: could you do a ranking of performance index as related to price, displaying performance per dollar?

    For gamers, the biggest point is how much time the GPU spends asking the RAM for data. Games that are more heavily CPU bound will probably see some benefit from faster RAM. It is worth noting that Dirt 3 seems to benefit the most from lower timings, as the lowest timings see the highest FPS. Undoubtedly, each GPU is waiting for information from RAM, and in turn, longer RAM latency means that each GPU has to wait for its chunk of data. Better titles will rely less on CPU and more on GPU, maybe Mantle will have some effect on this with reduced draw calls?

    Anyway, the price scaling on these "performance" RAM is so large that I couldn't in good conscience ever recommend anyone buying them when they would be better off spending it on a: dGPU, better dGPU, second dGPU.
  • freedom4556 - Monday, November 11, 2013 - link

    "Games that are more heavily CPU bound will probably see some benefit from faster RAM."
    Not according to nearly every review I've ever read on memory. Most reviews have all results within about 5 fps of each other regardless of game. Only synthetics really benefit. See articles like:
    http://anandtech.com/show/7364/memory-scaling-on-h...
    http://www.techpowerup.com/reviews/Avexir/Core_Ser...
    http://www.tomshardware.com/reviews/low-voltage-dd...

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