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Old 2013-11-02, 08:02   #1
mdettweiler
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Default RAM advice needed for laptop

Hi all,

I've been thinking for some time now about upgrading the RAM in my main laptop from 4 GB to 8 GB. This is mostly for non-prime-related stuff (4 GB is a little tight for day-to-day usage when you typically have at least one virtual machine and 5-10 browser tabs open - even without the VMs, browsers are getting sufficiently memory-leaky these days to make 4 GB smallish for average use), but I'd like to make sure I'm getting the best performance I can out of it for crunching as well.

The computer is an Acer Aspire 5552G-7641 - a "budget high performance" model as of early 2011. It has an AMD Phenom II X4 N970 processor (2.2 GHz, 4x512 KB L2 cache - roughly comparable per-core to a first gen mobile i5, i.e. pre-Sandy Bridge), and uses DDR3 RAM. The stock 4 GB (2x2 GB, I think) is running at 665.1 MHz according to CPU-Z.

Is this CPU even fast enough to warrant paying attention to the RAM clock frequency? That is, could it even come close to saturating the memory bandwidth when crunching on all 4 cores? (I mostly run LLR, which is similar to LL testing with Prime95 except a little lighter on the memory bandwidth, since it's typically used with exponents in the <5M range, i.e. smaller FFT sizes.)

My other question would be whether memory bandwidth could potentially make a difference for "normal" usage of the computer, notwithstanding prime-related tasks. At the moment, I'm being limited more by the HDD than anything (it thrashes frequently under the heavy loads I'm running), so compared to that I might not even notice the difference between, say, 1333 MHz and 1600 MHz.

If I do need to pay attention to RAM clock speed, is there a good way to figure out what's the fastest RAM my computer can handle? I've tried looking on Acer's website for detailed specs, but it's not particularly helpful in this regard. Keep in mind this is a laptop (a very hot-running one too), so overclocking is a moot point, and it probably doesn't have any BIOS controls to tweak the RAM clock, so I'll be stuck with whatever the motherboard "decides" to run it at. I really have no idea what that value would be, since the stock RAM is 665 MHz; I can only hope that it'll attempt to handle speeds higher than that (!).

Any advice from those more experienced with this is greatly appreciated! Most of my experience with this sort of things is with desktops (which I prefer to self-build), so I'm not particularly used to having to "reverse engineer" the system's capabilities like this.

Thanks!

Max

Edit: Oh, in case you were wondering, I'd love to upgrade it to 12 or 16 GB if I could, but unfortunately the MB doesn't support more than 8 GB.

Last fiddled with by mdettweiler on 2013-11-02 at 08:05
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Old 2013-11-02, 11:05   #2
Antonio
 
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According to
http://www.crucial.com/store/listpar...G-7641&Cat=RAM

it looks like you are using the fastest memory for that laptop.

I like the crucial website, it's never been wrong whenever I've checked for compatible memory for any of my machines.
You could try running their memory advisor software if you want to double check.
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Old 2013-11-02, 14:54   #3
BudgieJane
 
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I put 8GB memory in my Acer Aspire 5742. It didn't do much, apart from making it tale a little bit longer to start thrashing.
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Old 2013-11-02, 20:08   #4
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I made the upgrade to 8GB from 4GB in my Dell Inspiron N5010. Definitely a worthy investment. Like you said, day-to-day use can be taxing on a 4GB system. I saw some improvements in daily use and lots of improvements in anything more demanding, like a video game, for example.

I think it takes a very special kind of laptop to allow for overclocking. If you can't make any adjustments to your memory settings (which you probably can't) then you're actually going to want to pay special attention to what those "settings" actually are and look to get something identical, or as close to identical as possible.

Luckily, laptop RAM is much less diverse than desktop RAM. If your system is 1333 MHz then it probably runs 9-9-9-24 timings. If that is the case, then you can buy basically anything as all the 1333 MHz memory (you said 666 which translates to 1333 effective because of DDR3) has that set of timings.

The reason for that is if you went and bought some 1600 MHz memory, there might be a conflict between the memory wanting its settings and the motherboard wanting its settings. If the memory wins, you might be trying to boot at settings your CPU can't handle. If the motherboard wins, you're betting on the memory being happy to run at different settings.

There ARE standards for timings and frequencies, so the chances are a 1600 MHz 11-11-11-31 stick WOULD work at 1333 MHz 9-9-9-24. However, you're paying extra for something you're not getting.
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Old 2013-11-03, 04:20   #5
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If you want your machine to feel faster, I would spend the money on a decent SSD instead, such as the Samsung 840 Evo series. I have two of the 840 Pro's and they've been awesome. Evo is the newer version.

Sure, the RAM will help a tiny bit, but you'll be blown away by the SSD.
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Old 2013-11-04, 08:09   #6
mdettweiler
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Quote:
Originally Posted by Antonio View Post
According to
http://www.crucial.com/store/listpar...G-7641&Cat=RAM

it looks like you are using the fastest memory for that laptop.

I like the crucial website, it's never been wrong whenever I've checked for compatible memory for any of my machines.
You could try running their memory advisor software if you want to double check.
Ah, excellent--that's exactly what I was looking for! I'd forgotten they have that...I'll definitely keep it in the back of my mind for the future. I downloaded the advisor software, and it gave me the same results as the page you looked up from the model number. According to CPU-Z, my current memory is indeed running at 9-9-9-24 timings.

So, it looks like DDR3-1333 is the best I'm going to get. This is not too surprising, given that this is, well, a "budget high-performance" laptop, not really a true "high-performance" model. (It was $700 new, so definitely not in the same league as Alienware and the like who make the "real" high-performance laptops.) The CPU doesn't seem anywhere near powerful enough for memory bus saturation to be an issue (not like people are having with the latest Ivy Bridge and Haswell chips), so the difference in memory speed will likely be negligible for most purposes.

Regarding an SSD, yeah, those are amazing - I have one in my other laptop (an ultraportable tablet PC) and it's remarkably snappy for daily computing tasks. For my main box, though, it's not really an option at the moment since I already have a 500 GB HDD taking up the internal bay and it's nearly filled up as is...there's no way I could fit all that onto a remotely affordable SSD. I'm planning to build a new desktop computer a few years down the road to replace it and it will probably have an SSD boot drive (and a LOT more RAM!).

For now, my main priority is relieving the intense memory pressure I'm experiencing on a daily basis - since the system thrashes heavily basically every time I touch it, adding more RAM will do more than anything to improve performance.

Thanks all for your help - now that I know about the Crucial advisor program this should be much easier in the future!

Last fiddled with by mdettweiler on 2013-11-04 at 08:10
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