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Discussion Starter · #1 ·
If you're going to be buying any laptops with the new AMD "Trinity" A6, A8 or A10 APU in it (but this also applies to Llano A6 and A8 APUs), one of the most important things that should be checked is the RAM speed and config!

If your laptop pairs the A8 or A10 APU with DDR3-1333 memory as opposed to DDR3-1600 or better memory, be aware that you may be losing 20% of the potential performance, especially on the GPU side. Such a loss has been confirmed on Llano A8 APUs to be approximately 5-10%.

This is because when you pair a fairly bandwidth-responsive CPU (moreso than Intel processors) with the world's most powerful integrated graphics system, ever, which must share the available system memory as graphics memory, the result is a platform that is extremely bandwidth intensive. The interconnect between the CPU & GPU also uses the memory which is additionally responsible for the reason why bandwidth is extremely necessary (read below).

If you are buying a Trinity APU A6/A8/A10 laptop equipped with DDR3-1333, be prepared to see a noticeable boost in performance when you upgrade your RAM to DDR3-1600.

Try to avoid Trinity APU laptops with 6GB or other non dual-channel memory configs, or upgrade them to 8GB. Whichever works for you.

The best and most reliable RAM setup for mobile AMD Llano/Trinity APU has a symmetric dual channel 4GB (2x2GB) or 8GB (2x4GB) config at DDR3-1600 speeds or faster.

RECOMMENDED READING:

AMD Llano 6620G benchmarked with various RAM configs

LegitReviews - Testing Different Memory Speeds on AMD's A8-3850 Llano APU

HotHardware - In-Depth Analysis explains Llano's bandwidth sensitivity

REFERENCE BENCHMARKS (with AMD Llano generation 6620G graphics)

Note on asymmetric dual channel: In a 6GB config, asymmetric dual channel will allow the first 2GB in the 4GB DIMM and the other 2GB DIMM to be accessed as dual channel, but the remaining 2GB can only be accessed in single channel mode. This will provide performance that is close to a symmetric dual channel config, but this is not the most optimal configuration. There is still a small performance penalty to start with and there will be bigger performance penalties if RAM usage actually passes 4GB and addressing must revert to single channel. It is difficult to measure or determine where and when these penalties occur and in what games/programs the difference might be seen or not seen (i.e. check out the Crysis benchmarks below) and the random performance loss may throw you off course. A symmetric 2x2GB or 2x4GB setup is recommended for best and guaranteed performance).







If slow memory will bottleneck Llano APU, it will most certainly bottleneck the much more powerful Trinity APU!

Post updated: 9th Sept 2012
 

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Interesting to know of a processor that actually benefits from faster RAM (and one that you can see right in front of your eyes, not a small .00000000000000000000000000000000000001 FPS difference).
 

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Discussion Starter · #5 ·
Most reviews used DDR3-1600
 

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6GB isn't single channel. Of course it's best to use matched pairs, but a 4 + 2 GB setup will give you bandwidth somewhere between a 2 x 2GB and a 2 x 4 GB setup (may as well assume it'll be the slower of the 2).

Yes, lower-speed DDR3 will bottleneck a Trinity APU, but the Trinity 7660G isn't much faster than 6620G - perhaps by 20-30%. On the other hand, desktop Llano is clocked at 600mhz, compared to 444mhz for mobile Llano 6620G. So, it's very likely desktop Llano graphics are faster, or perhaps tied to Trinity mobile.

Also do note there will be zero Trinity laptops running with just one RAM slot. If it only comes with a single 4GB stick, it's not very hard to add a 2nd 4GB stick, and it's only $20. Of course it's something to consider, but your alarmist tone isn't necessary.
 

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Just when I was going to say 'xd has been prophetizing this for ages' I see you're the OP
biggrin.gif


It's nice that you warn before people start whining though
smile.gif
 

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Discussion Starter · #11 ·
Quote:
but a 4 + 2 GB setup will give you bandwidth somewhere between a 2 x 2GB and a 2 x 4 GB setup (may as well assume it'll be the slower of the 2)
Whaaa!?!?!?!?
Amount of RAM installed doesn't even affect bandwidth unless you have IMC limitations....

Quote:

Also do note there will be zero Trinity laptops running with just one RAM slot. If it only comes with a single 4GB stick, it's not very hard to add a 2nd 4GB stick, and it's only $20. Of course it's something to consider, but your alarmist tone isn't necessary.
The thing about making memory or whatever parts replacements/additions in laptops unauthorized is that doing so might void the warranty. It might not even be possible (or easily possible) if you have an ultrathin.
 

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I noticed that Samsung makes laptop versions of the 30 nm low voltage stuff, any info on how well the Samsung Wonder RAM performs with a Llano? I can hit 1900+ Mhz on this 555 rig, I am wondering if people can get it above 2000 with the better Llano memory controller?
 

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Discussion Starter · #13 ·
UPDATE: New results for Trinity APU... note that DDR3-1600 is now a slight bottleneck. However, this is on the desktop A10 5800k and the results may not be as representative with laptop Trinity APUs, which may see no bottleneck at DDR3-1600 speeds.

WoW Cataclysm:

mem%20wow%20average.png

mem%20wow%20min.png

Average FPS wise,DDR3-1333 provides 89% of the DDR3-1600 FPS (and is the difference between teary 50-55 FPS and smooth 60FPS) and just 81% of DDR3-1866 FPS. DDR3-1600 provides 91.6% of DDR3-1866 FPS, but higher binning and above-generic standard means that more DDR3-1600 kits are likely to have better overclocking capability.

Minimum FPS is where the improvements really kick in.

The WinRAR results make me curious:

mem%20winrar.png

Tom's did mention that:

Quote:
The situation isn't as compelling in WinRAR, which has historically demonstrated more sensitivity to memory bandwidth than any other application in our suite. Performance scales well through DDR3-1333, but as timings have to be loosened, higher latencies counteract the bandwidth increase, and WinRAR hits a ceiling of sorts.
There was no mention about the timings used at whatever speeds, but it has been hinted that the DDR3-1600 and 1866 results were taken at higher timings than the results for DDR3-1333. I wouldn't be surprised to see a bandwidth sensitivity to timings in this APU generation seeing as previous AM3 CPU generations have exhibited the same patterns.
 

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Discussion Starter · #14 ·
I'm going to bump this right now. I might even ask a mod to sticky this. There are a TON of Trinity APUs being sold with 6GB memory (single channel 4GB + 2GB) and the buyers are not realizing that they are being scammed and losing a huge slice of performance as a result of the memory deficit.
 

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Quote:
Originally Posted by xd_1771 View Post

I'm going to bump this right now. I might even ask a mod to sticky this. There are a TON of Trinity APUs being sold with 6GB memory (single channel 4GB + 2GB) and the buyers are not realizing that they are being scammed and losing a huge slice of performance as a result of the memory deficit.
If anyone could test an APU with 6GB vs. 8GB, same RAM speeds, I'd like to see the benches. 4GB + 2GB is dual-channel, mixed-pair, I already went over this, and would expect you (or any mod/former mod) to know as much. It's fairly hard to come by mixed pair vs. matched pair dual-channel benches.. will update when I find synthetic benches that I've seen on Tom's (synthetics show bandwidth, so if there's little/no bandwidth difference.. there will be little/no gaming performance impact.).

One more time, 4GB + 2GB is dual-channel. Once I aggregate sufficient data perhaps I should make a thread about it and have it stickied..
 

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Quote:
Originally Posted by jrbroad77 View Post

If anyone could test an APU with 6GB vs. 8GB, same RAM speeds, I'd like to see the benches. 4GB + 2GB is dual-channel, mixed-pair, I already went over this, and would expect you (or any mod/former mod) to know as much. It's fairly hard to come by mixed pair vs. matched pair dual-channel benches.. will update when I find synthetic benches that I've seen on Tom's (synthetics show bandwidth, so if there's little/no bandwidth difference.. there will be little/no gaming performance impact.).
One more time, 4GB + 2GB is dual-channel. Once I aggregate sufficient data perhaps I should make a thread about it and have it stickied..
I'm not even sure that's true.

Even still, snagging a set of 8GB 1866mhz RAM for your APU would supercharge it.

How long have I been going on about MEMORY BANDWIDTH now?
rolleyes.gif
 

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Quote:
Originally Posted by Imglidinhere View Post

I'm not even sure that's true.
Even still, snagging a set of 8GB 1866mhz RAM for your APU would supercharge it.
How long have I been going on about MEMORY BANDWIDTH now?
rolleyes.gif
Mobile trinity only goes up to ddr3 1600. Worth is subjective... Another 40 on ram can be a deal killer.

Feel free to do the research, 2 different sized sticks are indeed dual channel.. I've explained the concept before, either in this thread or another APU thread.
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sorry to ask, but what is the max memory speed trinity supports? i would assume 1866, but i just wanna be sure.
 
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