Memory Scaling on Haswell CPU, IGP and dGPU: DDR3-1333 to DDR3-3000 Tested with G.Skill
by Ian Cutress on September 26, 2013 4:00 PM ESTOur final set of tests are a little more on the esoteric side, using a tri-GPU setup with a HD5970 (dual GPU) and a HD5870 in tandem. While these cards are not necessarily the newest, they do provide some interesting results – particularly when we have memory accesses being diverted to multiple GPUs (or even to multiple GPUs on the same PCB). The 5970 GPUs are clocked at 800/1000, with the 5870 at 1000/1250.
Dirt 3: Average FPS
It is pretty clear that memory has an effect: +13% moving from 1333 C9 to 2133 C9/2400 C10. In fact, that 1333 C9 seems to be more of a sink than anything else – above 2133 MHz memory the performance benefits are minor at best. It all depends if 186.53 FPS is too low for you and you need 200+.
Dirt 3: Minimum FPS
We see a similar trend in minimum FPS for Dirt3: 1333 C9 is a sink, but moving to 2133 C9/2400 C10 gives at least a 20% jump in minimum frame rates.
Bioshock Infinite: Average FPS
While differences in Bioshock Infinite Minimum FPS are minor at best, 1333 MHz and 1600 C10/C11 are certainly at the lower end. Anything 1866 MHz or 2133 MHz seems to be the best bet here, especially in our case if we wanted to push for 120 FPS gaming.
Bioshock Infinite: Minimum FPS
Similar to Bioshock on IGP, minimum frame rates across the board seem to be very low, with minor differences giving large % rises.
Tomb Raider: Average FPS
Tomb Raider remains resilient to change across our benchmarks, with 1 FPS difference between the top and bottom average FPS results in our tri-GPU setup.
Tomb Raider: Minimum FPS
With our tri-GPU setup being a little odd (two GPUs on one PCB), Tomb Raider cannot seem to find much consistency for minimum frame rates, showing up to a 15% difference when compared to our 1600 C10 result which seems to be a lot lower than the rest.
Sleeping Dogs: Average FPS
Similar to other results, 1333 and 1600 MHz results give lower frame rates, along with the slower 1866 MHz C10/C11 options. Anything 2133 MHz and above gives up to 8% more performance than 1333 C9.
Sleeping Dogs: Minimum FPS:
Minimum frame rates are a little random in our setup, except for one constant – 1333 MHz memory does not perform. Everything beyond that seems to be at the whim of statistical variance.
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Rob94hawk - Friday, September 27, 2013 - link
Avoid DDR3 1600 and spend more for that 1 extra fps? No thanks. I'll stick with my DDR3 1600 @ 9-9-9-24 and I'll keep my Haswell overclocked at 4.7 Ghz which is giving me more fps.Wwhat - Friday, September 27, 2013 - link
I have RAM that has an XMP profile, but I did NOT enable it in the BIOS, reason being that it will run faster but it jumps to 2T, and ups to 1.65v from the default 1.5v, apart from the other latencies going up of course.Now 2T is known to not be a great plan if you can avoid it.
So instead I simply tweak the settings to my own needs, because unlike this article's suggestion you can, and overclockers will, do it manually instead of only having the options SPD or XMP..
The difference is that you need to do some testing to see what is stable, which can be quite different from the advised values in the settings chip.
So it's silly to ridicule people for not being some uninformed type with no idea except allowing the SPD/XMP to tell them what to do.
Hrel - Friday, September 27, 2013 - link
Not done yet, but so far it seems 1866 CL 9 is the sweet spot for bang/buck.I'd also like to add that I absolutely LOVE that you guys do this kind of in depth analyses. Remember when, one of you, did the PSU review? Actually going over how much the motherboard pulled at idle and load, same for memory on a per DIMM basis. CPU, everything, hdd, add in cards. I still have the specs saved for reference. That info is getting pretty old though, things have changed quite a bit since back then; when the northbridge was still on the motherboard :P
Hint Hint ;)
repoman27 - Friday, September 27, 2013 - link
Ian, any chance you could post the sub-timings you ended up using for each of the tested speeds?If you're looking at mostly sequential workloads, then CL is indicative of overall latency, but once the workloads become more random / less sequential, tRCD and tRP start to play a much larger role. If what you list as 2933 CL12 is using 12-14-14, then page-empty or page-miss accesses are going to look a lot more like CL13 or CL14 in terms of actual ns spent servicing the requests.
Also, was CMD consistent throughout the tests, or are some timings using 1T and others 2T?
There's a lot of good data in this article, but I constantly struggle with seeing the correlation between real world performance, memory bandwidth, and memory latency. I get the feeling that most scenarios are not bound by bandwidth alone, and that reducing the latency and improving the consistency of random accesses pays bigger dividends once you're above a certain bandwidth threshold. I also made the following chart, somewhat along the lines of those in the article, in order to better visualize what the various CAS latencies look like at different frequencies: http://i.imgur.com/lPveITx.png Of course real world tests don't follow the simple curves of my chart because the latency penalties of various types of accesses are not dictated solely by CL, and enthusiast memory kits are rarely set to timings such as n-n-n-3*n-1T where the latency would scale more consistently.
Wwhat - Sunday, September 29, 2013 - link
Good comment I must say, and interesting chart.Peroxyde - Friday, September 27, 2013 - link
"#2 Number of sticks of memory"Can you please clarify? What should be that number? The highest possible? For example, to get 16GB, what is the best sticks combination to recommend? Thanks for any help.
erple2 - Sunday, September 29, 2013 - link
I think that if you have a dual channel memory controller and have a single dimm, then you should fill up the controller with a second memory chip first.malphadour - Sunday, September 29, 2013 - link
Peroxyde, Haswell uses a dual channel controller, so in theory (and in some benchmarks I have seen) 2 sticks of 8gb ram would give the same performance as 4 sticks of 4gb ram. So go with the 2 sticks as this allows you to fit more ram in the future should you want to without having to throw away old sticks. You could also get 1 16gb stick of ram, and benchmarks I have seen suggest that there is only about a 5% decrease in performance, though for the tiny saving in cost you might as well go dual channel.lemonadesoda - Saturday, September 28, 2013 - link
I'm reading the benchmarks. And what I see is that in 99% of tests the gains are technical and only measurable to the third significant digit. That means they make no practical noticeable difference. The money is better spent on a difference part of the system.faster - Saturday, September 28, 2013 - link
This is a great article. This is valuable, useful, and practical information for the system builders on this site. Thank you!