RAM= Random Access Memory.
The Ram is used as a temporary storage device. Similar to the short term memory of humans. The computer will access information from your hard drive and store it in the RAM while the information is in use. When you close a program, the information for the program is wiped from the RAM. The more programs or windows you have open, the more RAM you are using. Similarly, the more you have open, the more your processor has to keep up with. More stuff running=Degrading performance.
The first step to increasing performance in your RAM is by deactivating un-necessary crap that runs in the background of Windows. Disable all Graphic services such as screen animations and the like. Make sure nothing starts up with Windows while it boots. You can do this by going to start and clicking on run and typing in "msconfig". Go to the startup panel and click on disable all and restart.
RAM operates differently than the CPU. Obviously, the more RAM you have, the more you can do. But, the clock speeds of RAM determine how fast it can communicate its information to the FSB and on to the CPU.
Firstly, open that program we download, CPU-Z. Go to the RAM tab see what your ram is. It will display detailed information for each stick of RAM you have. If you have 2 sticks of RAM and one operates slower than the other, then the faster one will under-clock itself to match the slower one.
DDR Ram was originally designed with a system divider ratio of 1:1. meaning that it ran at the same speed as the system FSB. If your Northbridge ran at 200 mhz, then your ram did as well. Therefore, increasing your FSB speed on a system running DDR ram, will subsequently cause your RAM speeds to increase as well. Beware though, there is a limit. For instance, I run DDR 333. If I try to clock my FSB higher than 333 (assuming my processor can handle it) then the RAM will fail because it cannot operate higher than 333.
DDR2 Ram is slightly different. Its speed is determined by a divider. I believe the divider is half of the FSB multiplier. For instance, if your multiplier is 14 then your divider will be 7. So if your CPU speed is 2800 MHZ, then you divide by 7 and that is the clock speed of your DDR2 ram. If I ran DDR2 ram on my computer, I would get a clock speed of 400 MHZ.
DDR3 operates similar to DDR2. Except it has a multiplier on top of the divider. The multiplier is 2 I think. So if your DDR3 ram is clocked at 800 MHZ then your FSB speed would be 400 MHZ. With a divider of 7 then the FSB multiplier is still 14 and resulting CPU speed is still 2800 MHZ.
The main differences between the 3 types of RAM are Operating speeds and Memory latencies.
The Latency time determines how fast or slow information is transferred from the RAMS data blocks into the FSB. DDR RAM has the lowest latency and therefore has the best performance in that case, but the clock speeds and data transfer bandwidth rates are much lower. When DDR2 first released, its performance was terrible in comparison to DDR because of the access latency rates. Since then, memory bandwidth and access frequencies have gotten much bigger.
When looking at latency numbers it is important to understand what the numbers mean. A Row Access Strobe latency of say 14 means that information is transferred into the FSB from the RAM every 14 CPU clock cycles. A cycle is determined by how many oscillations per second happen in a CPU. A CPU clocked at 2.8 GHZ will oscillate at 2,800,000 times per second. The information will transfer from the RAM and into the FSB every 14 cycles or 200,000 times per second.
The same numbers and math can be applied to the Column access strobe (CAS). By reducing the amount of clock cycles needed for each Strobe, you subsequently increase how much data gets into the FSB per second. If you adjust the numbers too low, you will cause the system to crash and overload.
And here we have it. The intimate knowledge that all overclockers should have.
edit on 18-9-2011 by Mr. Toodles because: (no reason given)