Does Cas Latency really make a difference?

Question

I have a MSI K8N Neo2 setup (AMD64 3500) and I am inquiring if memory latency effects are really noticible or not during heavy gaming or creating home movies for DVD's.  Currently, I have two sticks of Corsair Value Select 512MB DDR PC-3200 (VS512MB400).  It has a Cas latency of 2.5.  Is there any good noticible performance reason, I should trade up and buy some better performing memory.  If so, does anyone have a tried and true favorite with the K8N Neo2?  Any thoughts?  I have never overclocked, I just run at stock speeds.  Perhaps the performance gain is not worth the money?  
I also have:
eVGA geforce 6800NU
2- 200 GB Seagate IDE barracuda
Sony DVD burner
Enermax 465 watt PS
Hauppauge PVR 250
Netgear WG311v2
4 case fans
1 GB PC-3200

Answer 1

Spread Spectrum Modulation was invented to reduce interferences of high order
harmonics of the bus frequency. The theory is that, because every wave form
generates higher order harmonic waves or Obertoene, accumulation of the latter
can result in interference with the original signal.
One way to avoid this problem is to subject the base frequency to a slow (ca 100,000 clock cycles) modulation,
 meaning that the FSB varies between e.g. + and - 1% of the nominal value.
In older boards, usually two different settings were available,
either centered around the nominal value or set with the nominal frequency as the maximum (low modulation).
Most current boards employ the centered modulation.
This is, at least, the official version of Spread Spectrum Modulation.
In reality, there are different reasons for its implementation.
With increasing operating frequency, electronic components emit electromagnetic interference signals (EMI).
EMI, on the other hand can cause interferences with other devices and is,
 therefore, subject to regulation by the FCC which limits the signal amplitude according to its guidelines.
Any device exceeding the maximum allowable signal strength will not gain
 approval by the FCC and can, therefore, not be marketed.
In order to understand the reason for SSM, it is necessary to know how the FCC
tests EMI.
Basically, the testing device is a radio receiver and the testing is done by sweeping
its receiving frequency through the frequency range of interest and measuring the
interference with the video and audio signals. The bandwidth sensitivity of the
measuring device is in the order of about 1 MHz.
If the operating frequency is modulated to spread over a bandwidth of typically
4-5 MHz, the same will happen to the EMI spectrum and,
instead of showing a sharp peak, the spectrum will be spread to a more or less
Gaussian bell shape.
In this case, the amplitude will be, of course, substantially smaller, that is,
in the order of 1/3 - ¼ of the original peak.
The energy, however, will be the same. On the other hand,
the measuring instrument with its bandwidth limited to only 1/4 of the spread will,
consequently, only see 1/3 to ¼ of the EMI.
Therefore, the system will obtain FCC approval even if it exceeds the guidelines.
Recommended Settings
If running at stock setting, enabling Spread Spectrum Modulation (SSM)
may reduce EMI, and cause less interference with wireles communication devices.
Under all conditions, enabling SSM may cause a system to crash.
This is especially true for overclocking, simply because with the high multiplier values employed now, even a 0.5% modulation up and down can cause
differences up to as much as 10 MHz clock speed within one modulation cycle.
In other words, if the CPU is already operating at its limit, increasing the clock
speed by another 10 MHz may be fatal.
Therefore, for any overclocking, SSM should be turned off.
Another side effect of SSM is that it can interfere with the clock generator.
This means that, instead of merely initializing SSM, it is possible to enable FSB settings that were never supported by the manufacturer.
Examples are the Tyan Trinity 400 where disabling SSE results in an actual bus
speed of 90 MHz instead of the selected 117 MHz or the MSI 6309 where FSB settings of up to 200 MHz become available.
The reason is that activating SSM can cancel out the FSB setting since there
can be a pin address overlap on the clock generator chip.
(from lostcircuits.com)
Lets say your CPU is putting out EMI , its all concentrated on one "channel/frequency" on the spectrum.
What spread spectrum does is broaden that out to multiple channels/frequencies so it isn't as "potent" or interupting.
http://www.rojakpot.com/default.aspx?location=8&var1=0&var2=115
This is interesting.
Fsb spread spectrum enabled can cause internet dropouts.
http://www.asus.com.tw/support/faq/qanda.aspx?KB_ID=84823
If i can access it in bios i always have it disabled in any computer i'm maintaining.