Conclusions on Haswell-E DDR4 Scaling

When we first start testing for a piece, it is very important to keep an open mind and not presuppose any end-results. Ideally we would go double blind, but in the tech review industry that is not always possible. We knew the results from our DDR3 testing showing that outside of integrated graphics, there are a few edge cases where upgrading to faster memory makes sense but avoiding the trap of low base memory can actually have an overall impact on the system - as long as XMP is enabled of course. 

Because Haswell-E does not have any form of integrated graphics, the results today are fairly muted. In some ways they mirror the results we saw on DDR3, but are more indicative of the faster frequency memory at hand.

For the most part, the base advice is: aim for DDR4-2400 CL15 or better.

DDR4-2133 CL15, which has a performance index of 142, has a few benchmarks where it comes out up to 3-10% slower than the rest of the field. Cases in point include video conversion (Handbrake at 4K60), fluid dynamics, complex web code and minimum frame rates on certain games.

For professional users, we saw a number of benefits moving to the higher memory ranges, although for only very minor performance gains. Cinebench R15 gave 2%, 7-zip gave 2% and our fluid dynamics Linux benchmark was up +4.3%. The only true benchmark where 2800+ memory made a significant difference was in Redis, which is a scalable database memory-key store benchmark. Only users with specific needs would need to consider this.

There is one other group of individuals where super-high frequency memory on Haswell-E makes sense – the sub-zero overclockers. For these people, relying on the best synthetic test results can mean the difference between #5 and #20 in the world rankings. The only issue here is that these individuals or teams are often seeded the best memory already. This relegates high end memory sales to system integrators who can sell it at a premium.

Personally, DDR4 offers three elements of interest. Firstly is the design, and finding good looking memory to match a system that you might want to show off can be a critical element when looking at components. Second is density, and given that Haswell-E currently supports four memory channels at two modules per channel, if we get a whiff of 16GB modules it could be a boon for high memory capactiy prosumers. The third element to the equation is integrated graphics, where the need for faster memory can actually greatly improve performance. Unfortunately we will have to wait for the industry to catch up on that one.

At this point in time, our DDR4 testing is not yet complete. Over the next couple of weeks, we will be reviewing these memory kits individually, comparing results, pricing, styling and overclockability for what it is worth. Our recent array of DDR4-3400 news from Corsair and G.Skill has also got some of the memory manufacturers interested in seeing even higher performance kits on the test bed, so we are looking forward to that. I also need to contact Mushkin and Kingston and see if those CL12/CL13 memory kits could pose a threat to the status quo. 
Edit: Mushkin actually emailed me this morning about getting some product for review.

We have a couple of updates for our testing suite in mind as well, particularly the gaming element and are waiting for new SSDs and GPUs to arrive before switching some of our game tests over to something more recent, perhaps at a higher resolution as well. When that happens, we will post some more numbers to digest.

 

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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