RAM comparison for an APU

[Zeals]

Introduction:

APUs whether we like it or not are the future. All current Intel CPUs are technically APUs due to the presence of Intel HD graphics while AMD's 2014 road-map shows no further plans on the AM3+ platform with the focus being on FM2+ with Kaveri and their lower power mobile processors. On top of that integrated graphics performance has been increasing rapidly over the past couple of years with Intel Iris Pro providing a 50% performance boost over the previous generation while Kaveri will be boasting 856 GFLOPS which is roughly equivalent to a HD7750. With integrated graphics becoming a viable route for budget gaming rigs I've decided to do a comparison to find out the ideal RAM for an APU. We'll be doing this by using a 2x4 GB kit of G.Skill Ripjaws X with the speed set to different speeds to simulate the results you should expect. 

Note: these results may change going forward with newer architectures and the arrival of DDR4 in the future. 

 

Test Setup:

 

AMD A8-5600k @ 4 GHz

iGPU HD7560D @800gtGamer MHz

MSI A75MA-E35

G.Skill Ripjaws X 2x4GB (8GB)
Corsair VS450

Noctua NH-C12P

Windows 8.1 64 Bit

For the test setup I'll be using an A8-5600K which I have slightly overclocked similar to what Linus does, but my overclocks are extremely conservative so the vast majority of users should be able to obtain.

The CPU has been overclocked from 3.6 GHz to 4 GHz and the iGPU from 760 MHz to 800 MHz. The setup will also be using 768 Mb for the integrated graphics, I was originally intending to test the difference between 512 Mb, 768 Mb and 1 Gb but unfortunately my current BIOS version doesn't allow the user to set the amount of RAM dedicated to the iGPU.

We will be running three benchmarks. First will be 3D Mark Vantage run on the Performance Preset. The second will be Bioshock: Infinite which will be on 1280x720 (720p) on Medium graphics settings using the inbuilt benchmark. The final benchmark will be DotA 2 which will run at 1920x1080 (1080p) with the following advance settings with replay of the match Alliance vs Orange during the DotA 2 International 2013 being the test we run. 

 

Each of these benchmarks will be run with the following speeds: 1333 MHz, 1600 MHz, 1866 MHz and 2133 MHz. We'll be looking at the effects of clock speeds, timings and than a combination of both before reaching a conclusion. 

 

Results:

 

Clock Speed:

The first set of results we hold the RAM timings constant at 11-11-11-30 to see the impact of a flat speed increase without having to take into account the effects of timings. 

Note that DotA 2 would constantly crash at 2133 MHz while the system ran perfectly stable on the Vantage and Bioshock: Infinite. It should be noted that the A8-5600K is only rated up to 1866 MHz for memory, yet the motherboard I was using was able to go up to 2133 MHz on an OC, while BIOS options do allow us to go higher considering that one of the benches was crashing at 2133 MHz there was no point in going to 2400 MHz. Looking at the results there is a clear pattern showing the impact of higher the clock speed which does lead to better performance.

 

Timings:

Here we'll be holding the clock speed at a constant 1600 MHz and running the benchmarks at CL8, CL9, CL10 and CL11 to see any possible effects timings might have.

The results are interesting with there being little difference between the pairs CL8 and CL9 and CL10 and CL11, however there is a noticeable jump going from CL9 to CL10 which suggests that RAM timings do play a part in the performance and it isn't just about memory speeds with the sweet spot being below CL10.

 

Final Results:
In the final run we'll be looking at representative timings and speeds of RAM kits on the market, so a comparison between CL7 1333 MHz, CL8 1600 MHz, CL9 1866 MHz and CL11 2133 MHz. 

 

Conclusion:

Looking at the results we can conclude that the largest benefit to be gained from an iGPU would be from getting faster speeds. Given that in the current market of 8GB kits where there is virtually no difference in price going from 1333 MHz to 2133 MHz (Australian Pricing) it would seem wise to get the fastest RAM possible, however due to the stability issues that I faced with running a 2133 MHz kit which could be down to the RAM, the motherboard or the APU not supporting the speed properly. As a result I would recommend getting a 1866 MHz kit due to potential problems if you opt for a 2133 MHz. However given that majority of these kits can be overclocked and timings changed to reflect the other RAM kits, it doesn't matter too much which speed you opt for as long as the kit is high quality if you are willing to play around with timings and speeds in the BIOS. 

 

Video Overview: *Coming Soon*

 

Also any feedback is most welcome. If you want me to bench some other games suggest that below and I can take a look into it. 

[CwGoh]

Thanks! Great write-up that sheds quite a bit of light on the subject. Keep these coming!

[AndyCapets]

Great article man! I can finally proove to a stupid "friend" that bought 8gigs of HyperX Beast clocked at 2133mhz for way more than what I spent for my 8gigs of HyperX Beast clocked at 1600mhz because he thinks "it's better for gaming".. Newbies

BTW, what program did you use to make these graphs ?

[Zeals]

Great article man! I can finally proove to a stupid "friend" that bought 8gigs of HyperX Beast clocked at 2133mhz for way more than what I spent for my 8gigs of HyperX Beast clocked at 1600mhz because he thinks "it's better for gaming".. Newbies

BTW, what program did you use to make these graphs ?

Excel

[AndyCapets]

Excel

Oh ok, too bad I don't have it

[Marquee]

First of all great review.

I wanted to add something to this review. I have built a few APU systems and have done three sets of overclocking on APU's. I have found the Richland APU's like 6800K have a better (tweaked) memory controler. Which allowed Richland to more efficiently use higher speed RAM over Trinity. The future of APU's strongly relies on the use of faster RAM and tight timings. I would not be surprised if AMD's RAM came out in flavours of 2400, 2600, and 2800 for Kaveri launch. Also with the launch of DDR4 next year we can expect that APU's will get significantly more powerful.

 

Here is some of the testing I have done.

Video: http://youtu.be/vYhdkOq2LDo?t=2m33s

[WereCat]

Very nice review. Im planing to build one APU machine but not sooner than DDR4 MoBos will arive.

[flibberdipper]

I'll sum it up now for people who are too lazy to read it: MORE RAM AND FASTER RAM IS BETTER.

[kizoku_95]

Very detailed and informative. keep up your good work!

[mvitkun]

 

You should've tested dota on a diretide replay,diretide is so brutal,I lag on diretide with my gtx 480