Why Vista needs 4GB of RAM
17th Aug 2008 | 06:00
2GB of RAM is not enough for smooth Windows Vista performance. Here's why
Vista is a pig. It's a voraciously greedy resource hog that gobbles up more system resources than any previous operating system. That much is well documented.
It's baffling to note, therefore, that PC-buying punters remain seduced by the big, computational beasts of the component jungle. All too often, PCs are specced up with snazzy CPUs and graphics cards while scant regard is paid to that other performance-critical resource: system memory.
Every year, the likes of NVIDIA, Intel and AMD pour hundreds of millions of dollars into the development of bigger, better and faster chips. There's a similar investment in marketing, promotion and general punter prodding. Admittedly, it'd be easy to draw the conclusion that raw computing power is what you really need.
Improve your memory
But when it comes to day-to-day performance in Windows Vista, it's arguable whether such transistor-heavy chippery makes a significant difference. Put another way, you can throw as many CPU cores as you like at the problem of sludgy Vista performance. And you can wire up any number of 3D boards in multi-GPU rendering mode. If your rig doesn't have enough system memory, it's all for nought.
Conventional wisdom has it that 2GB of system memory is the price/ performance sweet spot for Windows Vista. But we're going to have to kick conventional wisdom out of bed on this one. For starters, he's a smelly old beast that feeds on lazy assumptions. But more to the point, he's just plain wrong. Anyone who has significant experience of Vista running with 4GB of RAM can tell you that. Vista runs much, much more smoothly with 4GB.
So, why the lack of focus on system memory despite the arrival of Microsoft's most resource-hungry operating system yet? Part of the explanation probably stems from the fact that demonstrating the benefits of slamming in the RAM isn't easy. Firing up a single benchmark application and letting rip does not get the job done. To prove our point, a slightly more sophisticated approach is required.
So how much do I need?
But if having heaps of RAM on hand is broadly a good idea, exactly how much do you need? Current conventional wisdom suggests 1GB is the absolute bare minimum for Vista while 2GB is the sweet spot in terms of bang for buck. Indeed, if you are currently enjoying a recently configured rig, there's a very good chance you are running 2GB.
That's plenty for operating systems with relatively modest memory footprints like Windows XP and Linux. But we're here to tell you it ain't enough for a really smooth experience in Vista. What's more, memory prices are now at ridiculously low levels – for old-school DDR2 DIMMs if not the latest DDR3 kit. Even a top-notch matched pair of 2GB DIMMs (4GB in total) boasting extreme cooling can be had for only £75.
So, let's not have any excuses. Compared to a powerful video card or CPU, trimming out your rig with 4GB is now eminently affordable. Before we look in detail at the benefits, however, there is one complicating issue that needs to be addressed. It involves the memory addressing limitations of the 32-bit build of Vista.
Four into 32 goes
In simple terms, all 32-bit operating systems hit the wall in terms of memory address space at 4GB. That's a function of the mathematics of 32-bit computing (for those who care, 32 binary bits can be represented in the decimal system as 232 or 4,294,967,296).
Unfortunately, things get significantly more complicated when 4GB is actually installed in a PC running a 32-bit operating system. Thanks to a feature known as memory mapped I/O reservations, not all 4GB are available for application and operating system use. Instead, some is reserved for certain hardware devices, to ensure driver compatibility, etc.
The precise amount reserved depends on devices installed. To quote Microsoft, "for example, if you have a video card that has 256 MB of onboard memory, that memory must be mapped within the first 4GB of address space. If 4GB of system memory is already installed, part of that address space must be reserved by the graphics memory mapping."
The manager lies
Typically, with 4GB installed and running Vista 32-bit, Windows will report somewhere between 3GB and 3.5GB of RAM available for use. However, with the release of Vista SP1, Microsoft has tweaked how Vista reports available memory. In System Properties, the full 4GB will be displayed. Fire up Task Manager and select the Performance tab and the truth will be revealed about the amount of memory that is actually available for the operating system and applications.
As for 64-bit versions of Vista, they have their own memory addressing limitations. However, these are not in fact due to any of the mathematical constraints of 64-bit computing, but are actually a function of Microsoft's product differentiation policy. Defective by design? BadVista.org thinks so…
Vista 64-bit Basic tops out at 8GB, Home Premium is good for 16GB and the Business, Enterprise and Ultimate will cope with a giddy-sounding 128GB. All of these assume that the system sports a 64-bit capable CPU, which includes all Intel desktop CPUs since the Prescott revision of the Pentium and AMD processors from the original Athlon 64 of 2003 and beyond. Motherboard support is also an issue beyond 8GB.
Four is more
We're guessing that you've already got a pair of 1GB sticks in your rig, but in order to show you what sort of increase is possible, we're going to use complete kits for the benchmarks. Enter, therefore, our candidates for demonstrating the upside of more memory, namely two 4GB kits as supplied by memory specialist Corsair. Yours for around £75, the 6400C4DHX is a DDR2 kit composed of a matched pair of 2GB 800MHz DIMMs.
Representing the latest DDR3 technology is Corsair's equally tongue-twisting 1600C9DHXNV kit. Once again, this is a pair of 2GB DIMMs, but this time running at 1,600MHz, which is at the top end of the performance stakes. While the £275 typical price point rather undermines the affordable 4GB argument, this kit will do a nice job of adding context in terms of clockspeed.
First of all, adding extra system memory is not a magic bullet that will kill all your performance problems. Many metrics of PC performance – including Windows boot times and most single-application benchmarks – get little or no benefit from extra memory beyond 2GB. If the application fits inside available system memory, adding more will have zero impact. However, bung a spot of application-juggling into the mix, and the resultant performance delta can be enormous.
A lot on
Imagine, therefore, the following multi-tasking scenario. You're happily hacking your way through a large library of high-res snaps from your latest holiday. Perhaps you have Photoshop open to buff up your mediocre photography skills. Maybe you're also a web junkie and as usual have whole heap of web pages on the go, too. OK, that's slightly contrived. But you get the idea: you're deep in multi-tasking territory.
If you're a gaming freak, eventually you'll want to fire up your favourite frag-fest in search of light relief. You then have the choice of whether to shut down all those open applications or leave the lot running in the background. Obviously if there was no performance penalty, that latter would, of course, be preferable. It's a lot less hassle. Problem is, if you try that with just 2GB of RAM in Vista, you'll pay a pretty severe penalty.
How big a penalty? For starters, it will take much longer to load up that game. A typical Call of Duty 4 level load time jumps from under 10 seconds on an otherwise well-specified PC to more than a minute and a half in heavy multi- tasking conditions. If that sounds bad enough, it gets even worse if you decide to Alt-Tab out of the game and go back to the desktop temporarily, perhaps to respond to an IM or send a quick email.
Fails to break four minutes
In our testing with a powerful quad-core PC running 2GB, it takes well over four minutes for application windows on the desktop to become fully responsive following such a manoeuvre. That's an excruciatingly long time. Indeed, not only is the process inordinately time-consuming, but the limited memory availability can lead to system instability and even crashes. In short, with 2GB of memory, it's not a realistic option.
So, what happens if you slam in a little more RAM? With 4GB installed, be it Vista 32-bit or Vista 64-bit, it transpires that game level load times are totally unaffected. To be more specific, our test involves approximately 20 multi-megabyte image files open in Photoshop, several PDF documents open and as many media-rich, flash-animated webpages on the go as you can shake a DDR2 DIMM at. But even with the slight loss of address space due to memory mapping, there's enough to contain most if not all of that as well as the whole of Call of Duty 4.
As for hopping back to the desktop, it's likewise a much, much less painful experience. You can expect to enjoy fully responsive access to the desktop and applications in less than 30 seconds.
Things get even better with the full access to all 4GB that Vista 64-bit delivers. In common with Vista 32-bit, game level load times are unaffected. But there's a really impressive bit. When you Alt-Tab back to the desktop from Call of Duty 4 – it is essentially instant – just the few seconds required by Vista to re-enable the 3D Aero interface is all that is required.
The explanation for this monumental difference in multi-tasking performance is actually pretty straightforward. With 2GB installed, there simply isn't enough RAM to store all that application data. A Windows operating system must therefore take a snapshot of the state of each application and cache it on the hard disk before proceeding to load the game data into RAM. Alt-Tab out of the game and you get the opposite process. The game state is saved to disk before retrieving the original desktop application data.
It's a process that's usually known as disk swapping and it will bring any PC – no matter how powerful – to a juddering, grinding halt. But why is it so much more prevalent in Vista? Mainly because Vista soaks up much more memory simply to sit in an idle state.
Clean boots at a cost
Inspect Task Manager following a clean boot of a freshly installed copy of Vista and you discover something pretty shocking. At least 700MB will have been snaffled up just to keep Microsoft's lumbering colossus alive and doing nothing of any note. On a 2GB rig, that leaves you with a little over 1GB of memory. In this brave new age of embedded video, multi-megapixel amateur photography and ubiquitous HD displays, that really isn't enough.
In multi-tasking terms, therefore, having a large amount of RAM to hand fundamentally changes the way you can use your PC without incurring a performance penalty. You no longer have to worry whether opening up a few more webpages, documents or images is going to spark off a brick-chewing cacophony from your hard drive and bring performance to a standstill. So, you can happily multi-task with almost infinite impunity and take that treacley, recalcitrant hard drive largely out of the equation altogether.
A little trickier to capture with benchmarks is the performance benefit of additional memory actually within resource-hungry games themselves.
Architects inspired by the wild
Developers tend to architect their games to suit the real PCs being used in the wild. Presently, 4GB systems remain relatively scarce. But although benchmark scores tend not to reflect any clear advantage of expanded memory availability, the subjective experience is a slightly different matter.
A good example is something like Oblivion. That title constantly loads data in the background as you explore the game universe rather than periodically calling a total halt to proceedings and loading the next section of the level, as with the likes of Half-Life 2. More memory makes for less disk swapping and a generally smoother experience.
Performance also tends to be a little smoother immediately after level loading in a really data-intensive title like Crysis. The data caching that takes place the first time you fire up a given level is that little bit less of an issue when you have more memory available, as our benchmark results reflect.
Poor memory causes instability
The situation can be even more critical with the most demanding RTS titles. When the poo is really interfacing with the rotational cooling device in the likes of Supreme Commander, limited system memory can actually cause instability.
In fact, Supreme Commander developer GasPowered has gone as far as to recommend the use of an advanced user patch from Microsoft that removes the 2GB address barrier that usually applies to any single application regardless of the amount of system memory available. Without the patch, some users find it is simply impossible to complete some of the larger, more advanced maps.
In the end, therefore, we suspect you will have to grudgingly admit that the benefits of having more than 2GB of RAM are probably broader than you imagined. And with memory so ludicrously cheap at the moment, this is an upgrade you really can't afford to ignore. Go on, do yourself a favour.