RAM is becoming a more reliable indicator of a phone's performance than CPU specs. After all, a dual-core processor can be far more powerful than an eight-core one these days
Exactly what RAM does is a little harder to grasp than a CPU's role, though. We're going to look into what RAM does in a phone, iOS or Android, and ask: how much of this stuff do we really need?
RAM stands for random access memory. This tells you any part of the data it stores can be accessed directly. The phone doesn’t have to scan through sequentially-stored data as you might do with a CD, an old tape cassette or, most importantly, a hard drive. It's effectively instant-access.
Today’s phones' general storage is random access too, because it’s comprised of eMMC chips rather than little spinning disc platters, but the most important distinction remains. A phone’s RAM is going to be much, much faster than the 8GB-64GB storage you use to store apps and music.
RAM is used to hold the data a phone, or any computer system, is currently using. That way the speed of the storage doesn’t become a bottleneck that slows the whole system down.
In the context of a phone, this means a chunk of an app’s data is loaded into RAM as soon as the app is started. Data is then shifted from RAM into a relatively tiny but even faster chunk of memory, the CPU caches, as it's dealt with.
If the CPU is a chef, the cache is their chopping board, RAM the kitchen cupboards, and general storage the supermarket 15 minutes down the road. That gives you an idea of how impossibly slow a phone would be if it really only used the kind of ‘memory’ we install apps onto.
RAM VS MULTI-TASKING
Just as important, RAM is also what holds the data that enables multi-tasking. Some mobile devices now offer real Windows-style multi-tasking, where two apps are running on-screen at once. A good amount of RAM is crucial for this.
The iPad mini 4 has 2GB RAM, and can perform real multi-tasking thanks to iOS 9. The iPad mini 3 with 1GB RAM cannot. This doesn't mean it would be impossible, of course, but that Apple thinks multi-tasking doesn't run well enough on a 1GB RAM device.
This isn’t the most important kind of mobile multi-tasking, though. RAM is also what lets you flick between apps without having to start from scratch each time. Even if an app isn’t actively doing anything in the background, RAM is used to create a saved state that the phone can zap back into as if you’d never left.
We take all this for granted, but have RAM to thank.HOW MUCH RAM DO YOU NEED?
This is the crux of why having more RAM is better. It lets a phone store more of these app snapshots without encroaching on the RAM a phone needs to make its OS run effectively.
Android and iOS do not run like Windows, though. With a desktop operating system it’s still possible to open far too many apps, to the point that the computer collapses into a juddering heap. I do this all the time, ending up annoyed at my laptop before realising it's only running poorly because I have 70 browser instances open and 100 3MB images loaded on Photoshop. It's my fault.
You can’t really misuse mobile operating systems in the same way because memory management happens automatically, and is more aggressive. Where with Windows you’d have to start closing apps when you stretch your RAM, iOS and Android simply offload app data from system RAM like a digital PA. Some apps may then still retain some of their ‘state’ data on the solid state storage, but at this point the app will have to reload fully when you return.
This is why a phone with barely enough RAM to keep its system running properly is going to be crap at multi-tasking. Leave at app, return 30 seconds later and you’ll have to wait just as long as you did when you first booted it up.
WHAT DOES 6GB RAM GET YOU?
If 2GB is the lower limit of RAM you’ll want in an Android phone, what’s the upper useful limit? While RAM itself isn’t going to use loads more power just by sitting there, any phone has to balance the benefits of keeping apps in active memory with the battery benefit of closing them down completely after a while, stopping any extra background processes.
The OnePlus 3 is the best example of this clash of priorities in action. It has 6GB RAM, the most of any big-name phone at release. It has 2GB more than the Samsung Galaxy S7 Edge, even though that phone is almost twice the price.
But is it useful? To start with, it actually wasn’t.