Doubling the RAM

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Introduction

You can see how, over time, the cost per MHz processor, per MB of memory and for GB hard disk, tend to fall and simultaneously increase the average characteristics of personal computers. Today it is quite common to have a 2 GHz processor for each core, hard disk capacity of 250 GB and 2 GB of RAM; some years ago instead on equal figure could reach only buy half gigabytes of RAM instead that two. But on the other hand, hand in hand also increase the minimum resources that the programmes, and especially video games, require to operate.

In parallel, the improvement of relations price / performance and price for quantity allows you to take into account not only the purchase of PCs more powerful, but also the upgrade of existing systems, components or simply adding new modules of RAM. And what about the impact on performance, most frequently is the doubling of system memory that brings more benefits. Increasing the quantity of RAM, in fact, improve the loading time of applications and increases the flexibility of multitasking.

This enhancement is not so obvious or immediate.

The performance of a computer in fact depend also on balancing performance that the various components are among them, the type of operating system that is adopted and applications that will be run.

Our analysis will focus on the benefits that can make have four gigabytes of RAM, a quantity that today no longer has a prohibitive cost.

But who needs a budget of this memory? Without going to mention professional applications, which often require even greater quantities four gigabytes, who uses graphics programs or video editing, although at amateur level, it can bind much system memory, especially if you run simultaneously other applications. But video games are sure to be the biggest and most widely distributed programs greedy memory. So is upon these that will focus our tests, although the considerations will have a general nature.

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Doubling the RAM to double the performance?

On a personal computer with 512MB of RAM and installed with Microsoft Windows XP, a doubling of system memory lead to an increased performance as to be perceived as a significant increase in speed. This example, very deliberately crude, has been done to highlight some key points of this issue.

First of all we talked about responsiveness of the system perceived by the user, which is very difficult to quantify by numbers or by using benchmarks. However, it is an assessment that daily each user's own computer, while awaiting the launch of the operating system, while launching more programs or want to switch from one window to another. Since these operations depend largely on how much memory available, there is a dependency between the speed with which they are performed and the quantity of RAM.

In second place is worth noting that nothing you're saying about other characteristics of the computer. This simplification allows us to more easily expose the arguments, but it is good to note that any benefits data from the RAM are also influenced by other. Referring to the example always original, the perception of doubling the speed of the system would diminish all the more because the frequency of the processor (single core) was less than 2 GHz. This is because the benefits data dall'aumentare the amount of memory would be limited by the performance CPU.

Why is it possible to perceive this increased responsiveness of the computer in front of a doubling of RAM?

Basically, with more system memory available to happen less frequently having recourse to the use of SWAP. Every time you start a program, its code and data needed to it are loaded into memory, in whole or in part, and when not in RAM remains more room for more data is needed to remove part of those present. If applications are now completed then the memory can simply be reassigned and overwritten, if the data are still useful to a program running then can not be lost and shall then place it in a special area on the hard disk, the area of SWAP.

Imagine now that the data just transferred onto your hard drive are again requested by a running program, we again transferred into RAM and if it is not enough space there should be a further operation SWAP.

Since all operations SWAP involving the hard disk, they require much more time reading or writing in RAM.

With a larger quantity of memory so you can manage more data without having to resort to SWAP and the switch from a running program to another, or even from one window to another, in this case is extremely faster.

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The limits in doubling of RAM

As we have seen so far, increase the amount of memory on a computer certainly brings benefits, although the effectiveness of the latter depends in part from the other components of your PC. However, it is not possible at will increase the quantity of RAM. On the one hand there is often a hardware limitation of the motherboard, which is related to the ability of each module of RAM installed, the other is the limit imposed by the features of the operating system used.

The 32-bit operating systems can use a maximum of 2 32 addresses, or can direct up to four gigabytes. It would therefore natural to deduce that you're able to manage an equivalent quantity of RAM, however, such addresses not only serve for the management of system memory but also for those devices that require MMIO (Memory Mapped Input-Output).

And 'as if, by simplifying, we had one hundred twenty labels but were confidential, then we could use up to eighty for our operations.

In particular, in the case of Windows operating systems, 4 GB of space available virtual address are evenly divided between applications and system. Therefore, in order to use more than two gigabytes of RAM is necessary to amend the parameter allocating these addresses, with a procedure known as RAM 4GT tuning. This makes it possible to reduce the addresses dedicated to the system and lead to a maximum of 3.3 those available for applications.

The 64-bit operating systems have available a greater number of addresses extremely well 2 64 corresponding to 16 terabytes, or more than sixteen thousand gigabytes. The amount of usable memory therefore varies according to the operating system installed.

Here is a summary table of the maximum memory installed Microsoft Windows XP and Vista.

As we can see from the table, all 64-bit systems allow you to reserve the necessary guidelines to the system, leaving much room for the use of four gigabytes of RAM.

For duty to chronicle also include the Physical Address Extension, which allows operating systems "professional" 32-bit to use more than 4 GB of system memory, as in the case of Windows Server 2008 Datacenter versions that and Enterprise has the limit 64 gigabytes.

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Test Configuration

Bearing in mind the considerations made in the preceding pages we decided to conduct the tests using Microsoft Windows Vista Ultimate 64-bit. For RAM we chose to use DDR3 configuration in 2x1 and 2x2 GB GB, in particular, we used dual channel kits XMS3 DHX of CORSAIR.

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Test

In tests there has been an increase in the average frame-rate when moving from two to four gigabytes of RAM, mostly limited to just one frame per second. This is first indication of an increase in absolute performance, as apparently content. But if we see improvements made to the values of the frame-rate minimum, observable in the benchmark done with World in conflict, we have reflected the true improvement offered by the doubling of RAM. The greatest amount of memory available reduces the negative peaks and, as expected, this increase is more consistent with increasing resolution and the size of textures.

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Conclusion

Moving from two to four gigabytes has its advantages, in terms of performance, with applications that make great use of system memory. The increase measured in tests with video games may not yet justify the upgrade for those who already have two gigabytes of RAM, however it is advisable to who is preparing to assemble a new computer, especially whether it will adopt a 64-bit operating system. Using a 32-bit OS you would still benefits from 2 to 4 GB, according to an increase in effective capacity by about 75%, although the fact of knowing that you will use a full just over three gigabytes, is certainly a psychological deterrent for buyers.

Surely the current configurations, even mainstream, are able to benefit from an allocation of 4 GB of RAM, increasing the responsiveness of the system and the ability to manage many applications "heavy" at the same time.

One step, one to 4 GB, certainly not necessary at all but now affordable to the pockets of many.