‘How much does memory speed matter?’ is a question often asked when dealing with mainstream processor lines.  Depending on the platform, the answers might very well be different.  Similar to our comparisons with Ivy Bridge, today we publish our results for 26 different memory timings across 45 benchmarks, all using a G.Skill memory kit.

In our previous memory scaling article with an Ivy Bridge CPU, the results of memory testing between DDR3-1333 to DDR3-2400 afforded two main results – (a) the high end memory kit offered up to a 20% improvement, but (b) this improvement was restricted to certain memory limited tests.  In order to be more thorough, our tests in this article take a single memory kit, the G.Skill 2x4GB DDR3-3000 12-14-14 1.65V kit, through 26 different combinations of memory speed and CAS latency to see if it is better to choose one set of timings over the other.  Benchmarks chosen include my standard array of real world benchmarks, some of which are memory limited, as well as several gaming titles on IGP, single GPU and multi-GPU setups, recording both average and minimum frame rates.

The Problem with Memory Speed

As mentioned in the Ivy Bridge memory scaling article, one of the main issues with reporting memory speeds is the exclusion of the CAS Latency, or tCL.  When a user purchases memory, it comes with an associated number of sticks, each stick is of a certain size, memory speed, set of subtimings and voltage.  In fact the importance of order is such that:

1.      Amount of memory

2.      Number of sticks of memory

3.      Placement of those sticks in the motherboard

4.      The MHz of the memory

5.      If XMP/AMP is enabled

6.      The subtimings of the memory

I use this order on the basis that point 1 is more important than point 3:

  • A system will be slow due to lack of memory before the speed of the memory is an issue (point 1)
  • In order to take advantage of the number of memory channels of the CPU we must have a number of sticks that have a factor of the memory channels (point 2), known as dual channel/tri channel/quad channel.
  • In order to ensure that we have dual (or tri/quad) channel operation these sticks need to be in the right slots of the motherboard – most motherboards support two DIMM slots per channel and we need at least one memory stick for each channel
  • If the MHz of the memory is more than CPU is rated for (1333, 1600, 1866+), then the user needs to apply XMP/AMP in order to benefit from the additional speed.  Otherwise the system will run at the CPU defaults.
  • Subtimings, such as tCL, are used in conjunction with the MHz to provide the overall picture when it comes to performance.

A user can go out and buy two memory kits, both DDR3-2400, but in reality (as shown in this review), they can perform different and have different prices.  The reason for this will be in the sub-timings of each memory kit: one might be 9-11-10 (2400 C9), and the other 11-11-11 (2400 C11).  So whenever someone boasts about a particular memory speed, ask for subtimings.

G.Skill DDR3-3000 C12 2x4GB Memory Kit: F3-3000C12D-8GTXDG

For this review, G.Skill supplied us with a pair of DDR3 modules from their TridentX range, rated at DDR3-3000.  This is at the absolute high end of memory kits, with very few memory kits going faster in terms of MHz.  Of course, in this MHz race, it comes at a price premium: $690 for 8 GB.  This memory kit uses single-sided Hynix MFR ICs, known for their high MHz numbers, and while there are large heat-spreaders on each stick, these can be removed reducing the height from 5.4 cm to 3.9 cm.

Hynix MFR based memory kits are used by extreme overclockers to hit the high MHz numbers.  Recently YoungPro from Australia took one of these memory sticks and hit DDR3-4400 MHz (13-31-31 sub-timings) to reach #1 in the world in pure MHz.

Test Setup

Test Setup
Processor Intel Core i7-4770K Retail @ 4.0 GHz
4 Cores, 8 Threads, 3.5 GHz (3.9 GHz Turbo)
Motherboards ASRock Z87 OC Formula/AC
Cooling Corsair H80i
Intel Stock Cooler (pre-testing)
Power Supply Corsair AX1200i Platinum PSU
Memory G.Skill TridentX 2x4 GB DDR3-3000 12-14-14 Kit
Memory Settings 1333 C7 to XMP (3000 12-14-14)
Discrete Video Cards AMD HD5970
AMD HD5870
Video Drivers Catalyst 13.6
Hard Drive OCZ Vertex 3 256GB
Optical Drive LG GH22NS50
Case Open Test Bed
Operating System Windows 7 64-bit
USB 3 Testing OCZ Vertex 3 240GB with SATA->USB Adaptor

With this test setup, we are using the BIOS to set the following combinations of MHz and subtimings:

Almost all of these combinations are available for purchase.  For any combination of MHz and CAS, we attempt that CAS for all sub-timings, e.g. 2400 9-9-9 1T at 1.65 volts.  If this setting is unstable, we move to 9-10-9, 9-10-10 then 9-11-10 and so on until the combination is stable.

There is an odd twist when dealing with DDR3-3000.  In order to reach 3000 MHz, as Haswell does not accept the DDR3-3000 memory strap, we actually have to use the DDR3-2933 strap and boost the CPU speed to 102.3 MHz.  This leads to a slight advantage in terms of CPU throughput when using DDR3-3000 which does come through in several benchmarks.  In order to keep things even, our 4.0 GHz CPU has the multiplier reduced for 3000 C12 in order to keep the overall system speed the same, albeit with a slight BCLK advantage.

At the time of testing, DDR3-3000 C12 was the highest MHz memory kit available, but since then there are now 3100 C12 memory kits on the market taking price margins even higher at $1000 for 8 GB.  The problem at this speed is the actual overclocking of the CPU aspect of the system will skew the performance results in favor of the high end kit.

Benchmarks

For this test, we use the following real world and compute benchmarks:

CPU Real World:
 - WinRAR 4.2
 - FastStone Image Viewer
 - Xilisoft Video Converter
 - x264 HD Benchmark 4.0
 - TrueCrypt v7.1a AES
 - USB 3.0 MaxCPU Copy Test

CPU Compute:
 - 3D Particle Movement, Single Threaded and MultiThreaded
 - SystemCompute ‘2D Explicit’
 - SystemCompute ‘3D Explicit’
 - SystemCompute nBody
 - SystemCompute 2D Implicit

IGP Compute:
 - SystemCompute ‘2D Explicit’
 - SystemCompute ‘3D Explicit’
 - SystemCompute nBody
 - SystemCompute MatrixMultiplication
 - SystemCompute 3D Particle Movement

For what should be obvious reasons, there is no point in running synthetic tests when dealing with memory.  A synthetic test will tell you if the peak speed or latency is higher or lower – that is not a number that necessarily translates into the real world unless you can detect the type and size of all the memory accesses used within a real world environment.  The real world is more complex than a simple boost in memory read/write peak speeds.

For each of the 3D benchmarks we use an ASUS HD 6950 (flashed to HD6970) for the single GPU tests, the HD 4600 in the CPU for IGP, and a HD 5970+5870 for a lopsided tri-GPU test.

Gaming:
 - Dirt 3, Avg and Min FPS, 1360x768
 - Bioshock Infinite, Avg and Min FPS, 1360x768
 - Tomb Raider, Avg and Min FPS, 1360x768
 - Sleeping Dogs, Avg and Min FPS, 1360x768

Firstly, I want to go through enabling XMP in the BIOS of all the major vendors.

Enabling XMP with ASUS, GIGABYTE, ASRock and MSI on Z87
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  • DanNeely - Thursday, September 26, 2013 - link

    A suggestion for future articles of this type. If the results mostly show that really slow memory is bad but above that it doesn't really matter, normalizing data with a reasonably priced option that performs well as 1.0 might make clearer. ex for the current results put 1866-C9 as 1.0, and having 1333 as .9x and 3000 as 1.02. I think this would would help drive home that you're hitting diminishing returns on the cheap stuff. Reply
  • superjim - Thursday, September 26, 2013 - link

    It looks like the days of 1600 C9 being the standard are over however the Hynix fire isn't helping faster memory prices any. 4-5 months ago you could get 2x 4GB of 1600 C9 for $30-35 bucks. Reply
  • Belial88 - Tuesday, October 01, 2013 - link

    That's because just like when HDD prices skyrocketed due to the 2011 Thailand Flood, RAM prices have skyrocketed due to the 2013 Hynix Factory Fire. Prices had started to rise around early 2013 due to market consolidation and some other electronics (tablet, console, etc market needs), nothing huge, and they were actually starting to drop until the factory fire.

    As for 1600 C9 being some sort of standard, well, what Intel/AMD specifies as their rated RAM speed is no more useful than what they specify their CPU speed, as we know the chip can go way above that. JPeople who are savvy and know how to buy RAM, can buy RAM easily capable of 2400mhz CL8 by researching the RAM IC.

    PSC/BBSE is easily capable of 2400mhz CL8 and generally costs ~$60 per 8gb (ie similar to the cheapest ddr3 ram). You can find some Hynix CFRs (double sided, unlike MFR, meaning they don't hit the high mhz numbers, but way better 24/7 performance clock for clock, kinda like dual channel vs single channel) for around $65, like the Gskill Ripjaws X 2400CL11 (currently like $75 on newegg), which will easily do ~2800mhzCL13.

    RAM speed has always made an impact, the problem with reviews like the above is assuming you can't overclock RAM, and have to pay for it. In reality there is only ~5 different types of RAM (and a few subtypes). If you are smart and purchase Hynix, Samsung instead of Spektek, Qimonda, you can get RAM that easily does 2400mhz+ for the same or simliar price as the cheapest spekteks. If you assume that going from 1600 to 2400 will cost you $100+, of course it's a ripoff...

    But if you buy, say, some Gskill Pi's 1600mhz for bargain bin, and overclock them to 2400CL8, you gain a good 10+ fps for almost nothing, and that's an awesome value. All RAM is just merely rebranded Spektek/Qimonda/PSC/BBSE/Hynix/Samsung, ie the same RAM is sold as 1600 CL9, 1600 CL8 1.65v, 1866 CL10, 2000CL11, 2133 CL12, etc ad nauesum.
    Reply
  • vol7ron - Monday, September 30, 2013 - link

    Relational results are helpful -I think they've been added since your comment- but I also like to see the empirical data as is also being listed.

    I know these things are currently being done in this article, I just want to make it a point not to make the decision to use one or the other, but both, again in the future.
    Reply
  • vol7ron - Monday, September 30, 2013 - link

    As an amendment, I want to add that the thing I would change in the future is the colors used. The spectrum should be green:good red:hazardous/bad. If you have something at 1.00x, perhaps that should be yellow, since it's the neutral starting position. Reply
  • alfredska - Monday, September 30, 2013 - link

    Yes, this is some pretty basic stuff. It seems there's bouncing back and forth between green = good/bad right now. The author needs to stick to a convention throughout the article. I'm not really of the opinion that green and red are the best choices, but at least if a convention is used I can train my eyes. Reply
  • xTRICKYxx - Thursday, September 26, 2013 - link

    It would be cool to see other IGP's including Iris Pro or HD 5000. Also, Richland may see slightly more than the 5% Haswell's HD 4600 has. Reply
  • Khenglish - Thursday, September 26, 2013 - link

    I would expect richland/trinity to have larger gains since the IGP has access to only 4MB cache instead of 6MB or 8MB found on intel processors. Reply
  • yoki - Thursday, September 26, 2013 - link

    hi, you said that the order of importance place amount of memory & their placement is most importance, but not a clue regarding how this scale in real world... for example i have 1600mhz 7Cl 6GB RAM in a x58 system,,,,should i upgrade it to 12GB ... how much i'll gain from that Reply
  • IanCutress - Thursday, September 26, 2013 - link

    That's ultimately up for the user to determine based on workload, gaming style, etc. I'd always suggest playing it safe, so if you plan on doing anything that would tax a system, 12gb might be a safe bet. That's X58 though, this is talking about Haswell, whose memory controller can take this high end kits ;) Reply

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