Back to memory information | All about Flash Memory

Firstly, when choosing some memory for your PC, no matter how much research you do, there will always be exceptions. The reality is that there are just too many variables that can affect the performance & function of memory in todays PC's.

We prefer that our customers use the enquiry forms below so that we can advise on the correct memory for their machine.

The key reasons to use this system are as follows:

• Clients who utilise the form receive a 100% money back guarantee in the event the memory is incompatible with their machine. If you choose the memory yourself and make a mistake, chances are it will be damaged and thus non-refundable.
• Users of the form receive a complete quotation including a shipping guide often with discounts otherwise unavailable.

General Memory Information

However, there are some basic rules you can follow which minimise the chance of problems:

1. Choose the correct speed memory for your motherboard.

To make life difficult for "you" the memory upgrader, memory manufacturers try to confuse the consumer by giving their products a variety of specifications which sound impressive or are perceived as faster by the potential buyer.

What you need to Know:

Front Side Bus (FSB) - This is the main information highway between your processor(CPU) and your memory. The faster the highway speed, the faster the memory you can use. You need to know your FSB speed in order to choose the correct Memory for your Machine.

Memory Bandwidth(PC???) - Some manufacturers use a specification like "PC2100" to describe the performance of their ram. In this case, the "2100" means 2100 Megbytes of information can be processed in one second. Obviusly, the higher the number the more information can be processed.

Memory Speed(DDR???) - Another way of specifying memory used by manufacturers is to use memory speed. In this case, "DDR400" means that the memory can run at speeds of up to 400Mhz.

BUS SPEED (FSB)	SPECIFICATION TYPE 1: BANDWIDTH BASED(Mb/sec)	SPECIFICATION TYPE 2: SPEED BASED(Mhz)
100Mhz	PC100	PC100 SDRAM
133Mhz	PC133	PC133 SDRAM
200 MHz	PC1600	DDR200
266Mhz	PC2100	DDR266
333Mhz	PC2700	DDR333
400Mhz	PC3200	DDR400
400Mhz	PC2-3200	DDR2-400
533MHz	PC2-4200	DDR2-533
667MHz	PC2-5300	DDR2-667

 

Can I use PC133 or PC100 SDRAM in my 66MHz PC?
Generally, all SDRAM is backward compatible and can run at any bus speed slower than it is rated to run. For example, a PC133 SDRAM DIMM is capable of running at 133MHz, 100MHz, and 66MHz. There are a few older motherboards that require 66MHz SDRAM and that will not accept PC100 or PC133 SDRAM, but they are the exceptions to the rule. Keep in mind that your memory will only operate as fast as the slowest link in your system. If you install PC100 SDRAM in your 66MHz PC, it will only run at 66MHz.

Should I buy a PC100 module or a PC133 module?
If your PC has a 133MHz front side bus (FSB), you will need PC133 SDRAM.If your PC has a 100MHz FSB, you can use PC100 or PC133 SDRAM. All PCs that accept PC100 SDRAM will also accept PC133 SDRAM; however, your memory will only run as fast as the slowest "link" in your system. If you have a 100MHz FSB or any PC100 modules installed, any PC133 modules that you install will only operate at 100MHz.

PC133 SDRAM doesn't offer any immediate benefit over PC100 SDRAM if you have a 100MHz FSB. However, if you are planning to upgrade to a system with a 133MHz FSB in the future, you may be able to use the PC133 modules you purchase now in your future system.

Can I mix and match PC100 and PC133 parts?
Generally you can mix PC100 and PC133 memory in the same system. The faster memory will run at the slower memory's speed (in this case PC100). However, there are some systems that will not correctly run this memory configuration. It is rare, but we suggest you contact your computer manufacturer or motherboard manual for specifics.

Why won't my motherboard accept 133MHz memory at a bus speed of 133?
There are several different bus settings in your motherboard's BIOS. Consult your motherboard manual to see if the proper settings are enabled and that the front side bus (FSB) is set correctly. You may also need to check the motherboard manufacturer's Web site to see if your board has the latest BIOS revision.

When should I choose PC133 Double Sided over Single Sided SDRAM?
Basically, if your motherboards supports a maximum of 256Mb per slot you need Double Sided Memory. If your motherboard supports 512Mb you can use single sided.

2. Check your BIOS.

Many manufacturers release motherboards capable of supporting future technologies. When those technologies are realised in the market place they update the BIOS to meet the needs of the new hardware. Thus, if upgrading your memory to a higher speed or larger size, check that the bios on your motherboard is up to date and actually capable of supporting the memory you wish to purchase.

3. Check your Processor

Sometimes the processor type will affect which memory you can use. For example, most Pentium 3 motherboards using PC133 will only support memory sizes up to 256Mb. However, Pentium 4 motherboards using PC133 will accept 512Mb simms. Check with your manufacturers website, or give us a call before purchasing.

4. Check your memory

1. If replacing/upgrading memory in your machine, make sure you get the same type & specification.
2. If adding extra memory to your machine try to find the same brand or at least the same specification.

If at all unsure about what to purchase for your machine please do the following:

1. Write down the brand & model number of your motherboard and memory, or alternatively take a digital photo.
2. Take note of your operating system type & version.
3. Send it to us via email so we can advise on the best option.

5. Check your operating system

Different operating systems support differing amounts of memory. Below is a basic guide for consideration:

Windows 95: 1Gigabyte - with alteration. Standard installs only recognise 512Mb
Windows 98: 1Gigabyte - with alteration. Standard installs only recognise 512Mb
Windows 98SE: 1Gigabyte - with alteration. Standard installs only recognise 512Mb
Windows ME: 1.5 Gigabytes
Windows NT: 4 Gigabytes
Windows 2000 Professional: 4 Gigabytes
Windows XP Home: 4 Gigabytes
Windows XP Professional: 4 Gigabytes
OS X: 16 Gigabytes due to current hardware limitations
OS 9.x: 1.5 Gigabytes
Linux: 64 Gigabytes