Overclocking Results

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 1619.36 78C
XMP, 2T to 1T 1611.44 79C
2600 10-12-12 No Post No Post

Subtimings Peak MHz PovRay OCCT Final PI
7-9-9 1866 1605.86 76C 267
8-10-10 2133 1606.57 77C 267
9-11-11 2400 1593.42 77C 267
10-12-12 2400 1599.21 77C 240
11-13-13 2400 1610.20 77C 218
12-14-14 2400 1594.08 78C 200
13-15-15 2400 1611.75 77C 185

I was a bit surprised that the memory kit would not add a memory strap to 2600 MHz with the same XMP timings.  This was confirmed in our secondary testing over sub-timings: 2400 C9 is the peak of our kit, giving a PI of 267.

IGP Compute Corsair Vengeance Pro 2x8GB DDR3-2400 C10 1.65V Conclusions


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  • Hairs_ - Saturday, December 14, 2013 - link

    A crossfire test is absolutely a valid metric, and testing with older generations of cpu and gpu is something I'm wholly in favour of. My issue is that if someone was buying a dual gpu setup, they would match the cards. If they upgraded after a time differential due to a budget concern, they might mix generations. I don't see a scenario where someone is buying dual+single, however, because if you had the budget to go for a top of the line dual card, you'd be better off with two cheaper cards in crossfire.

    Would people still have 4 gen old setups? Absolutely! Would they mix and match cards to suit a tight budget? Sure. Would any retail buyer follow *this* pattern? Vanishingly unlikely.
  • Egg - Sunday, December 15, 2013 - link

    Wait, why wouldn't you use a 5970 and a 5870? Sure you lose a bit on clock speeds but it's exactly the same as triple 5870 otherwise, isn't it? And you save some slots.

    Perhaps someone wanted to do a really expensive water cooled microATX build with 4 slots. IDK, but it doesn't sound that farfetched in practice.

    I haven't done this, or CF'ed anything at all, so this is just my two cents...
  • Hairs_ - Sunday, December 15, 2013 - link

    Why? Like I said, there's no physical reason why you *couldn't*, but people use crossfire/sli for the same reason people overclock: to get top-line performance out of a smaller budget. The other use scenario is someone who wants bragging rights and doesn't care about the cost.

    For the primary, that user is not going to pay for a top line dual card when they could get similar numbers from two lower end cards. For the secondary use case, if money is no object (which it would have to be), why wouldn't you have bought two 5970's?

    This example doesn't fit into any consumer behavior, so I have no idea why it would be used as a test.
  • Giffs - Friday, December 13, 2013 - link

    No idea if there is any point in using winrar 4.2
    But there is winrar 5.01 why not using the latest version? wouldn't it bring improvements on the software side and more accurate results of some sorte??
  • sinPiEqualsZero - Saturday, December 14, 2013 - link

    Thanks for the writeup. I'm shopping for memory and am happy I got to read this first.

    Also, I noticed an issue: " More expensive kits do not always equal performance, and as our benchmarks go, higher specification kits might also have little affect" should be effect with an e.

    Thanks, Ian!
  • Hairs_ - Saturday, December 14, 2013 - link

    There's no "might" about it. High spec kits make NO difference. Reply
  • Hairs_ - Saturday, December 14, 2013 - link

    I wonder how it is that the entirely arbitrary "Performance Index" which was devised for memory testing isn't at all borne out by real-world data. Yet the bald statement

    "From the data in our memory overview, it was clear that any kit with a performance index of less than 200 was going to have issues on certain benchmarks. The Corsair kit has a PI of 240, which is at the higher end of the spectrum."

    is still maintained.

    There are no facts to back this statement up, as proved in the tests. Are Anandtech reviews going to continue to ignore factual data in favour of preconceived assumptions? I hope not.
  • Ytterbium - Saturday, December 14, 2013 - link

    Explicit Finite Difference, in this graph you have 1333 C9 mid pack and 1866 C9 at bottom, I assume this is typo? Reply
  • Hairs_ - Saturday, December 14, 2013 - link

    if you look at all the graphs, the results aren't consistent at all. The kit that top one graph can be bottom of the next. Furthermore, the differences between top and bottom scoring kits is negligible in almost all tests, so many of the differences in rank can be due to statistical variance rather than a meaningfully measured performance difference.

    E.g. in many tests, the fastest kit in terms of headline mhz (3ghz) is beaten by theoretically slower stuff.
  • Gen-An - Saturday, December 14, 2013 - link

    I wonder if Corsair has purposely set out to make this kit look bad. Every single review I've seen of the Vengeance Pro 2x8GB 2400C10 kit has been Ver4.21, which uses Samsung 4Gbit B-die ICs and are infamous for not being able to clock much higher than about DDR3-2500 or so. I have four sticks of these and they are Ver5.29 using Hynix 4Gbit MFR and I've done Super Pi 32M runs at DDR3-3000 12-15-15-45 and they are rock solid at DDR3-2666 11-13-13. Reply

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