[GUIDE] How to find out if you can upgrade the RAM and which one you need

brummyfan2 said:

Nice work @aphanic, thanks for posting this useful information 

Thanks! I was noting an increase (or maybe it was always so) of threads asking for information on RAM upgrades and I thought having a full guide on the matter would be useful to direct people to. There will always be people who post without searching the community first, but at least it is written.

Kind of like giving someone a fish vs. teaching them how to fish, we will still help them choose the appropriate one, but they'd have a single place to learn about the matter.

pcarch said:

I am trying to plug a 16gb ddr3 ram into the only slot in order to upgrade my old notebook, the bios recognise it but cannot load up windows, any ideas what had gone wrong and how could I put it right?

Hi! Could you tell us the full laptop model and its main components? For example, if 16 GB were the maximum for the processor of that component it might have been only if it were divided in 2 slots, since you have just 1 that could be the issue. It is complicated to know sometimes without access to the designs of the manufacturer, and there's no way we get our hands in those, that's why it boils down to trial and error.

But we're lacking a lot of info to be able to assess the situation properly, I wouldn't be able to make an educated guess on why it happens (you're not alone though, a simple search in Google shows hundreds of cases like yours).

caloy said:

thank you. Very informative. I would like to ask if current setup has 4gb ram soldered with one free socket. Does it mean i can only up my ram 4gb more due to dual channel should match? 

You're welcome! And nope, you can upgrade it with more and retain some of the benefits. If my memory doesn't fail I had a different but similar unit like the one I used to write the thread (an A515-54, without the G) that had 4 GB soldered and a stick of 8 GB installed. Its total RAM was 12 GB and part of it was operating in dual channel mode, at least that's what was reported by some info and benchmarking utilities (you'd see speeds greater than those you can get on single channel).

Not all of the memory would work at that speed of course, I never made proper tests under that configuration, but my guess is that once 8 GB of memory are being used, the remaining 4 GB would perform in single channel mode.

Now that's interesting @pcarch! The max. number of memory channels there is related to how it can access the memory, grosso modo, how many of the slots it can access at the same time. For example, more than dual channel has only been seen in desktop chips or server ones (that I know of), where the memory bandwidth is more important; which makes me wonder why they designed that machine with 4 slots, piqued my interest.

For example, an even older Intel i7 967 Extreme was a 3 channel desktop chip, I think it was post Sandy Bridge when the successor to those 3-channel things established itself with quad channel designs, up until then even chips made for servers had 3 channel controllers as well. Quite different than those made for consumers though because they were able to address insane amounts of memory (think hundreds of GBs of RAM).

One of the first quad channel server chips from Intel must have been the E5-2637, a dual core chip with SMP (HyperThreading, so 4 logical cores) with a quad-channel memory controller. I know it's comparing apples to oranges looking at the specs of those 3 (the quad mobile chip you have, that desktop extreme with 3 channels and the server chip with 4 channels), but look at the difference in bandwidth:


i7 2630QM (Sandy Bridge):

i7 967 Extreme (Bloomfield, Nehalem microarch I think, precedes Sandy Bridge):

E5-2637 (Sandy Bridge EP):

I'm guessing those 51.2 GB/s of the server chip were achievable when using DDR3-1600, memory clocks of course influence the bandwidth, but still, look at what the difference dual vs tri vs quad channel makes.

That's why it's interesting to go for 2x 8 GB sticks vs. 1x 16 GB stick on most systems nowadays since dual-channel architectures seem to be the norm, there are videos on YouTube that demonstrate the difference like the one I'm going to post next, but the difference not only applies to games, it applies to everything!

https://www.youtube.com/watch?v=-k5wA7EFwpo

For gaming and video decoding it is specially interesting if the desktop/laptop in question only has available the graphics card that is integrated with the processor (unlike in that old video), because the main system memory becomes its video memory too (although if I'm not mistaken some AMD APUs used to integrate some video memory in the die too... I can't recall exactly).

But I digress as usual, going back to that 17'' laptop you had, it has a quad mobile chip, capable of dual channel and 4 memory slots. If we name the memory slots 1, 2, 3 and 4 and one has only 2 sticks to populate the thing, they ought to go to slots 1 and 3 (or 2 and 4, I think that worked too), no dual channel otherwise. At least that's how they're typically wired anyway, I'm sure there'd be an odd duck around, but that's the rule of thumb.

The 1600 MHz memory is downclocking to 1333 MHz for 2 reasons, to play nice with the other guys and also because that's the max the memory controller in that chip is able to handle. I'm wondering if you were to "play" with how the chips are plugged in, i.e. in which slots, if you'd be able to see any difference in bandwidth. There's a program, MaxxMem2, that should be able to show some you some numbers on the bandwidth you're getting in different configurations.

Aside from the fact that the we're comparing a mobile part to a desktop one, because they have different TDP and power consumption limits (which is probably the one of the reasons Apple will try to use ARM chips in their Macs, because they can up the power limits), does any of them have a dedicated card or are they using the ones integrated in the processor? Because AMD has always had the upper hand in there, they just perform better. iGPUs from Intel leave much to be desired.

I'm curious as to what they (Intel) is doing with their Xe branded iGPUs, if they're going to perform like they're claiming they will (and later on their discrete GPUs based on that); but for now if one is interested in light gaming and buying a laptop without any dedicated graphics card, AMD it is.