why did they pig up both memory slots?

[HalationEffect]

On one occasion(*) I encountered exactly that situation, where the decision on whether to spec a laptop's bill of materials with a single memory module or two modules with the same total capacity, was made purely based on price(**). Sure, I went ahead and extrapolated that it was probably not a unique event.

(*) Back in the late '90s, when I was working for the UK branch of PCChips (Hsing Tech Enterprise Co., Ltd, who have since merged with Elitegroup Computer Systems).

(**) I recall a conversation with one of the marketing guys, that whichever way the decision went, they could list it as a 'feature'. One module fitted = easier upgradability; two modules = improved performance.

[SteveRiley]

I always suspect that the main reason they do it, is that maybe a pair of modest capacity modules are cheaper than a single module of double the capacity (at the time of manufacture).

I think another reason they fill the banks might be to ensure that the user doesn't plug in an incompatible memory module in the open bank and create a performance problem.

I love this. Halation ascribes malice on the part of the laptop manufacturer, and Snowhog frets over user incompetence. These answers fit entirely within the personality profiles I've come to establish for each of you

[Teunis]

I've never seen any different than both slots being populated.
But on 4-slot machines there are typically only two in use, the speed gain of running two in parallel might indeed be the reason.

[whatthefunk]

RAM is so cheap these days that I dont think it will make any difference.

[Snowhog]

I think another reason they fill the banks might be to ensure that the user doesn't plug in an incompatible memory module in the open bank and create a performance problem.

[HalationEffect]

Assuming that your laptop supports dual channel memory access, it will be (slightly) faster with two memory modules than with just one, which is one reason manufacturers fill both slots.

I always suspect that the main reason they do it, is that maybe a pair of modest capacity modules are cheaper than a single module of double the capacity (at the time of manufacture).

[Tom_ZeCat]

My laptop has 4 GB of memory. I'm planning on installing VirtualBox soon, so I want to bump it up to 8. So I opened up the back panel for the first time to discover each slot occupied by a 2 GB memory card. ARG! I was hoping for a single 4 to be in there so I would only need to buy another 4. Instead I'm going to have to buy two 4s.

I'm going to do it anyway though. It will be way better to have 8 GB if I'm going to do the VirtualBox thingie. I'm planning on installing Windows 7 under Kubuntu so that I can run certain programs that won't run under WINE -- Final Draft 8 for one. I might even install Mac OS X, whichever version is the latest one that's been Hackintoshed. There is a version of Final Draft for Mac.