RAM and Latency... what you need to know

No one likes a slow computer. Well, at least notand usually only wields nominally performance gains.
anyone I know. People spend thousands of dollars onThere's no simple way to say it, so I'll apologize in
upgrades and cutting edge systems to use a fasteradvance for spitting some tech jargon your way. RAM
computer. However, upgrading your computer is nottiming are measured in CAS, RCD, RP, and RAS. CAS
the only way to have a quicker computing experience.refers to the amount of clock cycles to reach the
For those looking to squeeze the last bit ofcorrect column of memory, RCD refers to the amount
performance out of their machines, there are manyof cycles between RAS to CAS, RP refers to the
ways to optimize your system for speed.amount of cycles needed to close a row and open
Overclocking your CPU, tweaking your registry, andthe next row for reading, and RAS refers to the
fine tuning the bios are some the most common wayssmallest number of clock cycles a row must be
to optimize your system. Another often overlookedactively accessed. To simplify that explanation,
method is reducing your RAM's latency.remember that RAM timings are measured in FSB
RAM latency occurs when the CPU needs to retrieveclock cycles, so the lower the number, the faster your
information from memory. In order to receivesystem is.
information from RAM, the CPU sends out a requestFor example, my RAM timings are 3-3-3-8
through the front side bus (FSB.) However, the CPU(CAS-RCD-RP-RAS.) To optimize my timings, I first
operates faster than the memory, so it must waittried lowering my CAS in my bios to 2.5 and rebooting.
while the proper segment of memory is located andWindows booted just fine and everything worked
read, before the data can be sent back. RAM latencycorrectly, so I then rebooted and went back into my
is measured in wasted FSB clock cycles, since thebios and dropped my CAS down to 2, so now my
data is transferred through the FSB. The bigger thetimings were 2-3-3-8. Again, this setup seemed stable
latency number, the more FSB clock cycles it missed.so I went in and tried reducing my RAS, since it was
The goal in reducing latency is to get the data back topretty high. This was the last stable tweak that I could
the CPU in the least amount of FSB clock cyclesdo. When I tried to go below 2-3-3-7 in any timing my
possible.system either wouldn't boot or Windows would
The easiest way to reduce RAM latency is togenerate a mass amount of memory related areas. I
increase the speed of the front side bus. This meansused 3dMark 2005 to get an idea of how much
that the FSB can send and receive data between theimprovement my memory adjustments made, if any.
CPU and memory faster. However, this alsoBefore tweaking my timings I posted a 2105 3dMark
overclocks the CPU, RAM, and possibly the AGP busscore, after the tweaking I scored 2114. Not much of
as well. Overclocking your system will void yourdifference, but when it comes to optimizing your
computer's warranties and could possibly damage andsystem for speed, every last bit helps.
or destroy your system, so only attempt it if you'reWhile reducing RAM latency may not have a huge
willing to risk frying your computer. Adjusting your PC'simpact on system performance, it can give it a little
FSB is usually performed through the BIOS or throughextra kick, which combined with other methods of
jumpers on your motherboard, although not alloptimization, can result in a much quicker PC. So until
motherboards support overclocking.you're ready to buy a new computer, consider tuning
A safer method is to adjust your RAM's timings,up your current one to it's fullest potential.
although this can still potentially damage your system