How Much RAM Do You Need?

It's been said that you can never have enough money, and the same holds true for RAM, especially if you do a lot of graphics-intensive work or gaming. Next to the CPU itself, RAM is the most important factor in computer performance. If you don't have enough, adding RAM can make more of a difference than getting a new CPU!

If your system responds slowly or accesses the hard drive constantly, then you need to add more RAM. If you are running Windows XP, Microsoft recommends 128MB as the minimum RAM requirement. At 64MB, you may experience frequent application problems. For optimal performance with standard desktop applications, 256MB is recommended. If you are running Windows 95/98, you need a bare minimum of 32 MB, and your computer will work much better with 64 MB. 

Windows NT/2000 needs at least 64 MB, and it will take everything you can throw at it, so you'll probably want 128 MB or more. 

If you run Windows XP, it is probably in the range of 512 MB to 1 GB (get 2 GB to cover all your extra needs). 

Windows Vista (64-bit) lists 1 GB of RAM as minimum, 4 GB is recommended. 

Microsoft recommends a minimum of 1 GB of RAM for 32-bit versions of the Windows 7 operating system, and a minimum of 2 GB for 64-bit versions. If you plan on taking advantage of the Windows XP Mode feature, you should bump those requirements up to include an additional 1 GB of RAM. In general, it is highly advised to use 4 GB of RAM for both, especially if you're running a 64-bit version.

Linux works happily on a system with only 4 MB of RAM. If you plan to add X-Windows or do much serious work, however, you'll probably want 64 MB. Mac OS X systems should have a minimum of 128 MB, or for optimal performance, 512 MB.

The amount of RAM listed for each system above is estimated for normal usage -- accessing the Internet, word processing, standard home/office applications and light entertainment. If you do computer-aided design (CAD), 3-D modeling/animation or heavy data processing, or if you are a serious gamer, then you will most likely need more RAM. You may also need more RAM if your computer acts as a server of some sort (Web pages, database, application, FTP or network).

Multiple software threads that run all at once every time you boot up your PC continue to proliferate. Multitasking software includes what we really need, such as anti-virus tools or firewall software, or useful programs to which we have all grown accustomed that permanently run in the background until they need our direct attention. Most users, for example, have their email client and browser permanently available. Instant messengers such as AIM, ICQ MSN or YIM increasingly pop up on a growing number of desktops, while a media player plays music while you work. And all of these consume some memory, leaving fewer resources available for applications that you want to launch.

Another question is how much VRAM you want on your video card. Almost all cards that you can buy today have at least 16 MB of RAM. This is normally enough to operate in a typical office environment. You should probably invest in a 32-MB or better graphics card if you want to do any of the following:

• Play realistic games
• Capture and edit video
• Create 3-D graphics
• Work in a high-resolution, full-color environment
• Design full-color illustrations

When shopping for video cards, remember that your monitor and computer must be capable of supporting the card you choose.

Sources and Additional Information:

http://www.tomshardware.com/reviews/ram,1190.html

http://www.brighthub.com/computing/windows-platform/articles/16293.aspx

http://www.pcstats.com/articleview.cfm?articleID=2163

http://computer.howstuffworks.com/ram5.htm

Types of RAM on your PC

Introduction

The type of RAM doesn't matter nearly as much as how much of it you've got, but using plain old SDRAM memory today will slow you down. There are three main types of RAM: SDRAM, DDR and Rambus DRAM.

SDRAM (Synchronous DRAM)

Almost all systems used to ship with 3.3 volt, 168-pin SDRAM DIMMs. SDRAM is not an extension of older EDO DRAM but a new type of DRAM altogether. SDRAM started out running at 66 MHz, while older fast page mode DRAM and EDO max out at 50 MHz. SDRAM is able to scale to 133 MHz (PC133) officially, and unofficially up to 180MHz or higher. As processors get faster, new generations of memory such as DDR and RDRAM are required to get proper performance.

DDR (Double Data Rate SDRAM)

DDR basically doubles the rate of data transfer of standard SDRAM by transferring data on the up and down tick of a clock cycle. DDR memory operating at 333MHz actually operates at 166MHz * 2 (aka PC333 / PC2700) or 133MHz*2 (PC266 / PC2100). DDR is a 2.5 volt technology that uses 184 pins in its DIMMs. It is incompatible with SDRAM physically, but uses a similar parallel bus, making it easier to implement than RDRAM, which is a different technology.

Rambus DRAM (RDRAM)

Despite its higher price, Intel has given RDRAM its blessing for the consumer market, and it will be the sole choice of memory for Intel's Pentium 4. RDRAM is a serial memory technology that arrived in three flavors, PC600, PC700, and PC800. PC800 RDRAM has double the maximum throughput of old PC100 SDRAM, but a higher latency. RDRAM designs with multiple channels, such as those in Pentium 4 motherboards, are currently at the top of the heap in memory throughput, especially when paired with PC1066 RDRAM memory.

DIMMs vs. RIMMs

DRAM comes in two major form factors: DIMMs and RIMMS.

DIMMs are 64-bit components, but if used in a motherboard with a dual-channel configuration (like with an Nvidia nForce chipset) you must pair them to get maximum performance. So far there aren't many DDR chipset that use dual-channels. Typically, if you want to add 512 MB of DIMM memory to your machine, you just pop in a 512 MB DIMM if you've got an available slot. DIMMs for SDRAM and DDR are different, and not physically compatible. SDRAM DIMMs have 168-pins and run at 3.3 volts, while DDR DIMMs have 184-pins and run at 2.5 volts.

RIMMs use only a 16-bit interface but run at higher speeds than DDR. To get maximum performance, Intel RDRAM chipsets require the use of RIMMs in pairs over a dual-channel 32-bit interface. You have to plan more when upgrading and purchasing RDRAM.

Other Memory Types

• Credit Card Memory: Credit card memory is a proprietary self-contained DRAM memory module that plugs into a special slot for use in notebook computers.
• PCMCIA Memory Card: Another self-contained DRAM module for notebooks, cards of this type are not proprietary and should work with any notebook computer whose system bus matches the memory card's configuration.
• CMOS RAM: CMOS RAM is a term for the small amount of memory used by your computer and some other devices to remember things like hard disk settings.This memory uses a small battery to provide it with the power it needs to maintain the memory contents.
• VRAM: VideoRAM, also known as multiport dynamic random access memory (MPDRAM), is a type of RAM used specifically for video adapters or 3-D accelerators. The "multiport" part comes from the fact that VRAM normally has two independent access ports instead of one, allowing the CPU and graphics processor to access the RAM simultaneously. VRAM is located on the graphics card and comes in a variety of formats, many of which are proprietary. The amount of VRAM is a determining factor in the resolution and color depth of the display. VRAM is also used to hold graphics-specific information such as 3-D geometry data and texture maps. True multiport VRAM tends to be expensive, so today, many graphics cards use SGRAM (synchronous graphics RAM) instead. Performance is nearly the same, but SGRAM is cheaper.

How much RAM?

The amount of RAM memory used in modern desktop and laptop computers is expressed in megabytes (MB) and gigabytes(GB). A gigabyte (1GB) is 1024MB. Most desktop and laptop computers that came with Windows XP preinstalled came with 512MB. However, this increased to gigabytes when Windows Vista was released in January 2007. A computer with Windows Vista preinstalled should have a minimum of 2GB or RAM memory to run comfortably, however, 1GB of RAM memory in computers running a 32-bit version of Windows 7 should suffice, because the 32-bit versions of Windows 7 can run on a comparatively low-spec netbook computer, most of which currently only have 1GB of memory.

32-bit versions of Windows cannot use more than about 3.5GB of memory; 64-bit versions of Windows can support far more memory than most home users require. However, up to 4GB of memory, the 64-bit versions require twice as much memory as the 32-bit versions, so the minimum a 64-bit version should have is 2GB for Windows 7 and 4GB for Windows Vista. Most computers in use currently use a 32-bit version of Windows.

To find out which bit version of Windows you have, in Windows XP go Start => Control Panel and look for System and look on the General tab of the System Properties window. In Windows Vista choose the Classic View in the Control Panel. In Windows 7, just enter the word system in the Start => Search programs and files box to be provided with a clickable link to the System Properties window.

Sources and Additional Information:

http://www.computermemoryupgrade.net/types-of-computer-memory-common-uses.html

http://computer.howstuffworks.com/ram3.htm

http://www.pcbuyerbeware.co.uk/RAM.htm

http://whatis.techtarget.com/definition/0,,sid9_gci523855,00.html

Computer RAM Basics

Modern computer processors can perform several billion operations per second, creating and changing incredible amounts of data in a short period of time. To perform at this level, they have to be able to juggle the information they process, to have someplace to store it until it is needed again for modification or reference.

Computers have a memory structure which can be easily (if somewhat sloppily) compared to the human brain. The hard drive provides long-term memory storage similar to our long-term memories, a place where data is put to be permanently stored. RAM (Random Access Memory) provides a pallet that the computer can work from in normal operation, similar to our short-term memory. It holds information that is essential now but may or may not be transferred to long-term memory, depending on need.

Modern processors also include a memory cache, a comparatively small amount of high-speed memory which stores the data that is currently being used most often. This could be compared to our awareness, the memory that connects one moment to the next and keeps us doing what we were doing a second ago.

Random Access Memory (RAM) can be thought of as the short-term memory, in the sense that once the power is turned off, all information stored there is not saved. All modern computers have hard drives which store data permanently as magnetic information, but even with the improved speed of today's hard drive technology. Hard drives are still too slow to keep up with the needs of the processor since it can operate on considerably more information per second than can possibly be transferred to and from the hard drive.

This is where the need for a fast, short-term memory solution comes in, a memory space that provides very fast access for the processor so data can be written and read as needed without slowing down the system appreciably.

RAM fulfills this need, specifically DRAM (Dynamic RAM), the template for all modern memory types.

DRAM consists of semiconductor chips arranged on a small circuit board, each containing a logical arrangement of cells laid out in rows and columns. These cells use a combination of a capacitor and a transistor to achieve one of two states, filled with electrons (1) or empty (0), thus allowing binary (digital) information to be stored.

A capacitor is like a small bucket that is able to store electrons. To store a 1 in the memory cell, the bucket is filled with electrons. To store a 0, it is emptied. The problem with the capacitor's bucket is that it has a leak. In a matter of a few milliseconds a full bucket becomes empty. Therefore, for dynamic memory to work, either the CPU or the memory controller has to come along and recharge all of the capacitors holding a 1 before they discharge. To do this, the memory controller reads the memory and then writes it right back. This refresh operation happens automatically thousands of times per second.

This refresh operation is where dynamic RAM gets its name. Dynamic RAM has to be dynamically refreshed all of the time or it forgets what it is holding. The downside of all of this refreshing is that it takes time and slows down the memory.

Sources and Additional Information:

http://www.pcstats.com/articleview.cfm?articleID=985

http://www.howstuffworks.com/ram.htm

http://www.overclock.net/amd-memory/525103-ram-basics-explained.html

http://www.encyclopedia.com/video/UGww9i0gXTk-computer-basics-what-is-ram.aspx

Virtual Memory Optimization in Windows Computers

What is Page File?

A key to improving your PC’s performance is the page file (also called the swap file and/or virtual memory). A page file is a cache of data on your hard drive; this cache is used to supplement your computer’s main memory (RAM). When a computer runs out of memory, it uses the page file. Since data access on a hard drive is slow compared to accessing memory, your PC’s performance takes a hit.

What is exactly Virtual Memory?

In a 32-bit computer, the memory addresses are 32 bits long and stored as binary (base 2) numbers. There are approximately 4 billion possible different 32-bit binary numbers (2^32=4,294,967,296). Because of this, there is a 4GB limit for addressable memory in a 32-bit computer.

A program instruction on an Intel 386 or later CPU can address up to 4GB of memory, using its full 32 bits. Each process is assigned an address space of 4GB of virtual memory, regardless of the amount of available physical memory. Each process is isolated from the rest and has its own 4GB address space. This means that the 4GB addressability limit applies on a per-application basis, not across all applications taken together.

This is normally far more than the RAM of the machine. The amount of physical memory on the computer is not related to the amount of memory address space. If a computer has 256MB of physical memory, there is still a 4GB memory address space, and if a computer has 8GB of physical memory, there is still a 4GB memory address space.

Applications are not allowed direct access to physical memory. When an application requests more memory, Windows maps some physical memory (as long as some is available) into the process’s address space.

The hardware provides for programs to operate in terms of as much as they wish of this full 4GB space as Virtual Memory, those parts of the program and data which are currently active being loaded into Physical Random Access Memory (RAM). Windows maintains several tables that keep track of all of this, and the application knows only about the virtual memory address.

The processor itself then translates (‘maps’) the virtual addresses from an instruction into the correct physical equivalents, doing this on the fly as the instruction is executed. The processor manages the mapping in terms of pages of 4KB each - a size that has implications for managing virtual memory by the system.

Why do I need page file optimization?

Optimizing your page file when you’re running low on RAM is always a good idea. When all physical RAM in a computer is in use, Windows starts using the hard disk as if it were additional RAM. This is why we have a Page file (also called the swap file). Because RAM memory is a lot faster than the hard disk, whenever the computer begins to use the Page file to relieve memory pressure, we begin to experience drastic performance degradation.

One of the most effective things you can do to improve performance is ensure that there is enough RAM available to avoid frequent paging (swapping) of memory contents between disk and RAM.

This means that the actual limit on the memory used by all applications is the amount of RAM installed plus the maximum size of the Page file.

How much swap space do you need? That depends the amount of RAM you have and the programs you use. The current algorithm Windows uses to set the default paging file size is:

• If total physical RAM is less than 2 gigabytes (GB), the paging file is set to 1.5 times the amount of RAM or 2 GB, whichever is smaller.
  
• If total physical RAM is equal to or more than 2 GB, the default size is set to 2 GB.

Note that in Default Windows settings the setup amounts of initial and maximum page files are different. It is recommended to make its initial size as big as the maximum size. Although this will cause the Page file to occupy more HD space, we do not want it to start off small, then having to constantly grow on the HD. Writing large files (and the Page file is indeed large) to the HD will cause a lot of disk activity that will cause performance degradation. Also, since the Page file only grows in increments, you will probably cause Page file fragmentation, adding more overhead to the already stressed HD.

Should You Disable Your Page File?

Several experts suggest that you disable the page file to increase performance, by doing away with the page file that means your computer won’t have to access the hard drive. So it should be faster, right? It can be, or it can cause several instability problems for your computer. Many programs won’t even run without a page file enabled. The effect definitely depends on the amount of physical memory available. The 8 GB RAM systems might run just like normal, but when you lower the amount of memory available to 2 GB, system instability will definitely be visible.

Page File configuration

For simplicity of the task, you might follow the Microsoft recommendations listed above for the amount of the Page file settings. However, you can go further and set it according to particular needs of your computer, which require more time and more experience.

Open System Properties, then the Advanced tab and press the Performance Settings button, selecting the Advanced tab, finally pressing the Change button. Select the Drive which XP is installed to and set the Paging file size for selected drive to Custom size, setting the Initial size and Maximum to 1500MB according to the basic recommendations. If you have multiple drives available ensure these are set to No paging file. Click Ok and restart as required for the changes to take effect.

You can stop right here if you do not want to go deeper and you are satisfied with standard settings. Otherwise, you can continue with recommendations below.

After computer reboot press Ctrl + Alt +Delete simultaneously and load the Task Manager, selecting the Performance tab. This tab allows use to monitor peak Virtual Memory use (The Peak value in the Commit Charge (K) section). This window can be minimized and you should then run your most resource intensive Applications in order to see just how Virtual Memory is utilized. Once you’re satisfied with your testing switch back to Task Manager.

The Peak value records maximum Virtual Memory use during the session, in K, e.g. in the image above 324548K. Dividing this amount by 1024 gives you the value in MB - 317MB in this instance. For improved stability this value should be padded, so add at least 50MB to this value, e.g. 317MB should be increased to 400MB. This provides us with a Minimum Page File size to use. If the real demand of virtual memory is different, you can tweak the original settings.

Once more open System Properties, select the Advanced tab and press the Performance Settings button, selecting the Advanced tab, finally pressing the Change button.

A few general points to recall before you do anything;
If you have only 1 Hard Drive, split into multiple partitions, the Page File should be set to the partition XP is installed to, you should not create multiple Page Files for different partitions in this case, i.e. 1 Hard Drive = 1 Page File.

If you have multiple Hard Drives installed it is beneficial to locate the Page File on the Hard Drive XP is not installed to; but only where the other Hard Drive is of a similar or better performance, e.g. if you have a SATA Drive and ATA 100 Drive the Page File should be located on the SATA Drive regardless as it is notably faster.

The Page File should not be located on a mirrored Drive, e.g. RAID array, if possible as fault tolerance/backup is not required and may decrease performance.

How to overcome the 4GB limitation for page file in Windows?

When you set the paging file size in Windows, the documentation states that the largest paging file that you can select is 4,095 megabytes (MB). This limit is imposed by the page mapping that we use on x86 processors. These processors cannot handle more pages per page file. This is the limit set per volume; you can actually create paging files this large on one or more drives if you need a larger paging file. If extra drives or volumes are not available, you can create multiple paging files on a single drive by placing them in separate folders.

To create multiple paging files on one volume to overcome the 4,095-MB limit:
1. On the drive or volume you want to hold the paging files, create folders for the number of paging files you want to create on the volume. For example, C:’Pagefile1, C:’Pagefile2, and C:’Pagefile3.
2. Click Start, Click Run, type regedit in the Open box, and then click OK.
3. In the left pane, locate and click the following registry subkey:
HKEY_LOCAL_MACHINE’System’CurrentControlSet’Control’SessionManager’MemoryManagement
4. Find the Pagingfiles value, and then double-click it to open it.
5. Remove any existing values, and add the following values:
c:’pagefile1’pagefile.sys 3000 4000 c:’pagefile2’pagefile.sys 3000 4000 c:’pagefile3’Pagefile.sys 3000 4000
6. Click OK, and then quit Registry Editor.
7. Restart the computer to cause the changes to take effect.
8. Access the virtual memory settings to check the properties of the paging file. To do this, follow these steps.

Sources and Additional Information:
http://www.petri.co.il/pagefile_optimization.htm
http://g4tv.com/techtvvault/features/36099/Optimize-Windows-XP-Page-File.html
http://support.microsoft.com/kb/237740
http://www.pctipsbox.com/speed-up-windows-by-optimizing-your-page-file/
http://www.techspot.com/tweaks/memory-winxp/memory-4.shtml