This guide covers system memory only, not graphics card memory.
Timings, voltages, brands - it goes over everyone's head at one point. But with yet another easy guide of mine, I'm sure you'll soon understand it! If you need to know anything about RAM before purchasing, you should take a look here!
RAM (Random Access Memory) comes in many forms, but you don't need to worry about most of them:
RAM really isn't that hard to understand. Admittedly, it looks very complicated from the outside - but really it isn't that difficult to understand once you understand the basics:
You should always check your QVL (Qualified Vendors List) for your motherboard
Timings:
5-5-5-12, 3-2-3-5 - it looks concerningly difficult, but it really isn't! Once you break it down, it isn't really that hard to understand. So when 5-5-5-12 is broken down into parts, it would be: CAS-tRC-tRP-tRAS - now you are probably concerned already! But don't be. If you want more detail on these you can PM me, but all you need to realize is that lower timings are better (4-4-4-12 > 5-5-5-12), but you shouldn't spend a lot more on getting lower timings unless you would be seriously tweaking your system!
CAS = Represents the number of cycles that have to pass before the memory can locate the 'hex address' of a memory cell (complicated, but you really don't need to know this - lower is better)
tRC = Memory is stored like a grid inside the RAM. tRC represents the time that has to pass before it locates the column and row inside the RAM (again, complicated - but all you need to know is that lower is generally better)
tRP = Same as tRC basically, although this is the time it takes before it gets to the next cell (complicated yet again, lower is better!)
tRAS = The time it takes from the command being received and when it actually starts it (generally, this number can be as high as 18, but all you need to know is that lower is better)
If you see RAM that displays its speed and then something like C3 or C4 after that, this means that the timings will generally be 3-3-3-X or 4-4-4-X
Voltages:
Voltages can vary from 1.6V to 2.5V - but you just need to check your motherboard's QVL to make sure that they work on your board. You shouldn't be concerned with your voltage unless you consider tweaking your system (and that you know it works on your system).
Understanding DDR:
Double Data Rate RAM is quite simple to understand. 800MHz RAM is actually "400Mhz x 2" RAM. SD is not like this, only DDR - hence the name Double Data Rate.
Speeds:
PC2100 = 266MHz (aka DDR266)
PC2700 = 333MHz (aka DDR333)
PC3200 = 400MHz (aka DDR400)
PC2-3200 = 400MHz (DDR2)
PC2-4200 = 533MHz (DDR2)
PC2-5300 = 667MHz (DDR2)
PC2-5400 = 667MHz (DDR2)
PC2-6400 = 800MHz (DDR2)
PC2-8500 = 1066MHz (DDR2)
PC2-8888 = 1111MHz (DDR2)
PC2-9200 = 1150MHz (DDR2)
The maximum non-overclocked DDR speed is 400MHz. Certain brands make 500MHz DDR RAM. This is just overclocked RAM.
Cooling:
Most good RAM brands (except for Value ranges) come with good heatsinks, and generally this is enough cooling for your RAM. However, if you think that you want more cooling on it - there are dedicated RAM coolers that seem to work on most motherboards!
Dual Channel:
Image you have 2 DIMMs (sticks) of RAM. Both have 64-bit data channels (64 chosen because generally, a 512MB DIMM is made up of 8 very small chips actually on the RAM - each 64-bit). When in dual channel, this becomes a single 128-bit. Basically, you are sticking them together into one, but it means that you are able to move data from the RAM to the CPU (in theory) twice as quickly.
Overclocking RAM:
Whenever you increase the CPU speed, your BIOS might automatically increase (or decrease the speed of your RAM). So when you overclock, you are not only overclocking your CPU, but also your RAM. With small overclocks (eg. E6400 2.1GHz to 2.5GHz), the RAM speed might decrease to PC2-5300 speeds, but you can easily put it back up to PC2-6400 and it will put hardly any more stress on your RAM / CPU. You shouldn't overclock or tweak your RAM voltages / speeds unless you know what you are doing!
.. basically, that is really all you need to know. You just need to check your QVL (Qualified Vendor's List) to make sure that your RAM will work on your motherboard.
______________________________
RAM RECOMMENDATIONS
For the lazy and incompetent (you skipped down here, I can insult you), here's a small list of some recommended RAM at different prices. DDR2 only!
______________________________
Corsair 1GB XMS2-5400C4 : $50 - £35
Aimed for motherboards that can only accept a maximum of 667MHz and are on a budget (ie. can only afford 1GB)
______________________________
Crucial 2GB Ballistix PC2-5400C3 : $245* - £60
Aimed for motherboards that can only accept a maximum of 667MHz but still want a minimum of 2GB
* Overpriced, possibly!?!
______________________________
Corsair 1GB XMS2-6400C4 : $70 - £55
Aimed for systems on a budget, but want the best speed possible (ie 1GB but fast)
______________________________
Corsair 2GB XMS2-6400C4 : $115 - £100
Onto more powerful RAM. For people who crave quantity, quality and speed.
______________________________
OCZ 4GB PC2-6400C5 : $235 - £200
Aimd to either extreme enthusiasts, or for those in media / graphics who require maximum performance.
______________________________
.. and that's about it!
Enjoy,
kyle.
Timings, voltages, brands - it goes over everyone's head at one point. But with yet another easy guide of mine, I'm sure you'll soon understand it! If you need to know anything about RAM before purchasing, you should take a look here!
RAM (Random Access Memory) comes in many forms, but you don't need to worry about most of them:
| Guide | Picture | Comments |
|---|---|---|
| SDR (Single Data Rate) | Here | This is old, old RAM. It is never used in newer systems because it runs at very slow speeds |
| DDR (Double Data Rate) | Here | More commonly found on slightly older systems, such as systems that use AMD Athlon 64 Single Cores |
| DDR2 (Double Data Rate 2) | Here | Most new CPUs utilize this type of RAM. It is faster, more powerful and the works with Core 2 Duo and AMD AM2 |
| DDR3 (Double Data Rate 3) | Here | This is the latest type of RAM but it isn't used at the moment |
RAM really isn't that hard to understand. Admittedly, it looks very complicated from the outside - but really it isn't that difficult to understand once you understand the basics:
You should always check your QVL (Qualified Vendors List) for your motherboard
Timings:
5-5-5-12, 3-2-3-5 - it looks concerningly difficult, but it really isn't! Once you break it down, it isn't really that hard to understand. So when 5-5-5-12 is broken down into parts, it would be: CAS-tRC-tRP-tRAS - now you are probably concerned already! But don't be. If you want more detail on these you can PM me, but all you need to realize is that lower timings are better (4-4-4-12 > 5-5-5-12), but you shouldn't spend a lot more on getting lower timings unless you would be seriously tweaking your system!
CAS = Represents the number of cycles that have to pass before the memory can locate the 'hex address' of a memory cell (complicated, but you really don't need to know this - lower is better)
tRC = Memory is stored like a grid inside the RAM. tRC represents the time that has to pass before it locates the column and row inside the RAM (again, complicated - but all you need to know is that lower is generally better)
tRP = Same as tRC basically, although this is the time it takes before it gets to the next cell (complicated yet again, lower is better!)
tRAS = The time it takes from the command being received and when it actually starts it (generally, this number can be as high as 18, but all you need to know is that lower is better)
If you see RAM that displays its speed and then something like C3 or C4 after that, this means that the timings will generally be 3-3-3-X or 4-4-4-X
Voltages:
Voltages can vary from 1.6V to 2.5V - but you just need to check your motherboard's QVL to make sure that they work on your board. You shouldn't be concerned with your voltage unless you consider tweaking your system (and that you know it works on your system).
Understanding DDR:
Double Data Rate RAM is quite simple to understand. 800MHz RAM is actually "400Mhz x 2" RAM. SD is not like this, only DDR - hence the name Double Data Rate.
Speeds:
PC2100 = 266MHz (aka DDR266)
PC2700 = 333MHz (aka DDR333)
PC3200 = 400MHz (aka DDR400)
PC2-3200 = 400MHz (DDR2)
PC2-4200 = 533MHz (DDR2)
PC2-5300 = 667MHz (DDR2)
PC2-5400 = 667MHz (DDR2)
PC2-6400 = 800MHz (DDR2)
PC2-8500 = 1066MHz (DDR2)
PC2-8888 = 1111MHz (DDR2)
PC2-9200 = 1150MHz (DDR2)
The maximum non-overclocked DDR speed is 400MHz. Certain brands make 500MHz DDR RAM. This is just overclocked RAM.
Cooling:
Most good RAM brands (except for Value ranges) come with good heatsinks, and generally this is enough cooling for your RAM. However, if you think that you want more cooling on it - there are dedicated RAM coolers that seem to work on most motherboards!
Dual Channel:
Image you have 2 DIMMs (sticks) of RAM. Both have 64-bit data channels (64 chosen because generally, a 512MB DIMM is made up of 8 very small chips actually on the RAM - each 64-bit). When in dual channel, this becomes a single 128-bit. Basically, you are sticking them together into one, but it means that you are able to move data from the RAM to the CPU (in theory) twice as quickly.
Overclocking RAM:
Whenever you increase the CPU speed, your BIOS might automatically increase (or decrease the speed of your RAM). So when you overclock, you are not only overclocking your CPU, but also your RAM. With small overclocks (eg. E6400 2.1GHz to 2.5GHz), the RAM speed might decrease to PC2-5300 speeds, but you can easily put it back up to PC2-6400 and it will put hardly any more stress on your RAM / CPU. You shouldn't overclock or tweak your RAM voltages / speeds unless you know what you are doing!
.. basically, that is really all you need to know. You just need to check your QVL (Qualified Vendor's List) to make sure that your RAM will work on your motherboard.
______________________________
RAM RECOMMENDATIONS
For the lazy and incompetent (you skipped down here, I can insult you), here's a small list of some recommended RAM at different prices. DDR2 only!
______________________________
Corsair 1GB XMS2-5400C4 : $50 - £35
Aimed for motherboards that can only accept a maximum of 667MHz and are on a budget (ie. can only afford 1GB)
______________________________
Crucial 2GB Ballistix PC2-5400C3 : $245* - £60
Aimed for motherboards that can only accept a maximum of 667MHz but still want a minimum of 2GB
* Overpriced, possibly!?!
______________________________
Corsair 1GB XMS2-6400C4 : $70 - £55
Aimed for systems on a budget, but want the best speed possible (ie 1GB but fast)
______________________________
Corsair 2GB XMS2-6400C4 : $115 - £100
Onto more powerful RAM. For people who crave quantity, quality and speed.
______________________________
OCZ 4GB PC2-6400C5 : $235 - £200
Aimd to either extreme enthusiasts, or for those in media / graphics who require maximum performance.
______________________________
.. and that's about it!
Enjoy,
kyle.
Last edited by leetkyle (2007-07-12 14:30:55)