Comparing DDR3 to DDR4

Moving from a standard DDR3-2133 C11 kit to DDR4-2133 C15, just by looking at the numbers, feels like a downgrade despite what the rest of the system is. Ideally we want the first number, the frequency, to be high and the second number, the latency, to be low. After spending several years dealing with DDR3, moving to DDR4 feels a bit of a backwards step when you look at solely the numbers on paper.

As part of this review we have covered many different areas where DDR4 is the upgrade of DDR3, not only in terms of voltage but some of the underlying concepts as well. This puts DDR4 in a position for upgradability in the future, especially when it comes to density and future technologies (see the next page for more information). But an ultimate question still remains: at the same frequency and latency, do they perform the same?

The only way to perform an identical comparison would be to have a platform that could probe both DDR3 and DDR4 while keeping the same CPU. If one comes along, we will test that, but in the mean time we can do some broad comparisons with near-identical systems.

For this test we took two Haswell based systems and compared them against each other. The first contains the Haswell-E i7-5960X processor, cut it down to run at four cores with no HyperThreading, fixed the CPU speed at 4 GHz and placed the memory into DDR4-2133 14-14-14 350 2T timings. We did the same with the second system, a Haswell based i7-4770K moved it to 4 GHz and making sure it was in 4C/4T mode. The OS was placed into a unique high performance profile and we ran our test suite. The only difference that remained between the two setups was the L2 and L3 cache, which we cannot change unfortunately.

In our non-gaming tests, there is one situation where DDR3 is more than 3% better and two where DDR4 is +3%. It is worth noting that most of the numbers, especially with things like the Web and Cinebench are actually slightly negative.

In the gaming tests, similarly there are more +3% on the side of DDR4. If we do a direct comparison regardless of the percentage, DDR4 wins 11 times compared to DDR3 getting 8, and almost of DDR3’s wins are minor except for two-way SLI. It would seem that for two-way SLI DDR4 at least brings up some of the minimum frame rates.

Pulling out the >3% difference numbers, just to see what the numbers exactly are:

On the face of it, the Hybrid result does not seem that different, whereas a full minute on Photoscan or 10 seconds in our WinRAR test feels like a difference. In the gaming tests moving nearer to 120 FPS or 60 FPS, especially in both of the minimum frame rate tests, is an important jump which happens with DDR4.

Overall, comparing DDR4 to DDR3, there is little difference to separate the two. In a couple of small instances one is better than the other, but on those edge cases it might be prudent to say that we cannot make a final decision until we can synchronize the rest of the system, such as the size of CPU caches. When we can perform such tests, we will run some more numbers.

Memory Scaling on Haswell: 2x GTX 770 SLI Gaming The Future of DDR4
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  • dgingeri - Thursday, February 05, 2015 - link

    Really, what applications use this bandwidth now?

    I'm the admin of a server software test lab, and we've been forced to move to the Xeon E5 v3 platform for some of our software, and it isn't seeing any enhancement from DDR4 either. These are machines and software using 256GB of memory at a time. The steps from Xeon E5 and DDR3 1066 to E5 v2 and DDR3 1333 and then up to the E5 v3 and DDR4 2133 are showing no value whatsoever. We have a couple aspects with data dedup and throughput are processor intensive, and require a lot of memory, but the memory bandwidth doesn't show any enhancement. However, since Dell is EOLing their R720, under Intel's recommendation, we're stuck moving up to the new platform. So, it's driving up our costs with no increase in performance.

    I would think that if anything would use memory bandwidth, it would be data dedup or storage software. What other apps would see any help from this?
    Reply
  • Mr Perfect - Thursday, February 05, 2015 - link

    Have you seen the reported reduction in power consumption? With 256GBs per machine, it sounds like you should be benefiting from the lower power draw(and lower cooling costs) of DDR4. Reply
  • Murloc - Thursday, February 05, 2015 - link

    depending on the country and its energy prices, the expense to upgrade and the efficiency gains made, you may not even be able to recoup the costs, ever.
    From a green point of view it may be even worse due to embodied energy going to waste depending on what happens to the old server.
    Reply
  • Mr Perfect - Friday, February 06, 2015 - link

    True, but if you have to buy DDR4 machines because the DDR3 ones are out of production(like the OP), then dropping power and cooling would be a neat side bonus.

    And now, just because I'm curios: If the max DDR4 DIMM is 8GB, and there's 256GB per server, then that's 32 DIMMs. 32 times 1 to 2 watts less a DIMM would be 32 to 64 watts less load on the PSU. If the PSU is 80% efficient, then that should be 38.4 to 76.8 watts less at the wall per machine. Not really spectacular, but then you've also got cooling. If the AC is 80% efficient, that would be 46.08 to 92.16 watts less power to the AC. So in total, the new DDR4 server would cost you (wall draw plus AC draw) 84.48 to 168.96 watts lower load per server versus the discontinued DDR3 ones. Not very exciting if you've only got a couple of them, but I could see large server farms benefiting.

    Anyone know how to work out the KWh and resulting price from electric rates?
    Reply
  • menting - Friday, February 06, 2015 - link

    100W for an hour straight = 0.1KWH. If you figure 10-20 cents per KWH, it's about 1-2 cents per hour for a 100W difference. That's comes to about $7-$14 per month in bills provided that 100W is consistent 24/7. Reply
  • menting - Thursday, February 05, 2015 - link

    pattern recognition is one that comes to mind. Reply
  • Murloc - Thursday, February 05, 2015 - link

    physical restraints of light speed? Isn't any minuscule parasitic capacitance way more speed limiting than that? Reply
  • menting - Thursday, February 05, 2015 - link

    there's tons of limiting factors, with capacitance being one of those. But even if you take pains to optimize those, the one factor that nobody can get around is the speed of light. Reply
  • menting - Thursday, February 05, 2015 - link

    i guess i should say speed of electricity in a conductive medium instead of speed of light. Reply
  • retrospooty - Friday, February 06, 2015 - link

    Agreed if an app required high total bandwidth it would benefit.

    Now see if you can name a few that actually need that.
    Reply

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