how much of an issue is latency

Tiny

New Member
i found the following:

Geil Value 1Gb PC3200 Dual Chan DDR Kit (2x512MB) High Speed CL (5ns Cas 2.5 6-3-3) Aluminium heat spreader – 164.44

and

2x PQI 512MB PC4000 DDR TurboMemory with Platinum Colour Heatspreader (3-4-4-8) – 153.92

i notcied that the latency on the PQI was higher than the geil so i assume that this is why it is cheaper, but the pqi is pc4000, so my question is, is latency that much of an issue? how does it effect the performance of the memory.

thanks
 

Praetor

Administrator
Staff member
i notcied that the latency on the PQI was higher than the geil so i assume that this is why it is cheaper, but the pqi is pc4000, so my question is, is latency that much of an issue? how does it effect the performance of the memory.
You got two choices:
1. Higher latency, higher clock
2. Lower latency, lower clock.

You benifit from a lower latency if your transfers need to initiate faster and thry are tiny or you do a lot of within-stick and within-bank transfers. You benifit from higher clocks for everything else (specifically anything that requires big trasfers). Damn near everyone on the planet will benifit from a higher clock (which is why you see people overclocking their CPUs rather than trying to cut the latency down).

Now consider the two modules you've got there (both benched via 2Ghz running 200Mhz core -- which doesnt exist but its just a quick analysis):
GEIL
Latency: 75ns (150cycles)
Initial Response Time: 50ns
Theoretical Bandwidth: 6400MB/s
PQI
Latency: 97ns (194cycles)
Initial Response Time: 40ns
Theoretical Bandwidth: 8000MB/s
It becomes a fairly obvious answer (which is why i cant understand people who buy low-latency RAM and try to keep it low.... they make low latency RAM so that they can be raised higher ...)
 
Top