Memory Timings

Hi, I was viewing the memory timings in BIOS and noticed a setting marked "Burst Length in Clocks" which was the 5th one on the list. I also noticed there are two values, "4" and "8". I was wondering, in general, how those two values relate to one another, ie: is 4 considered "looser" or "tighter" than 8. In other words, if I was overclocking and was looking to loosen the timings, would this be a parameter to look at? - Thanx

 

Burst mode for RAM -- generally speaking -- allows the system to perform multiple reads in sequence without waiting for CAS delay. You would get 1 read for every clock cycle compared to 1 read cycle and 2 to 3 for CAS latancy. Burst mode can only be used to read memory from the same row, and (I think) it can only be used to read consecutive memory addresses. I don't think there's a burst write mode, but I might be wrong. Be awhile since I've looked at it.

Presumably, the number listed is the number of sequential reads the system tries to perform before allowing for the CAS delay. 8 would offer the highest number of sequrntial reads (the burst lasts for 8 clock cycles), but because you're bursting and not allowing the CAS to take place (which "refreshes" the SDRAM and allows the state to be read) I suspect you increase the likelyhood of RAM read errors. If you're overclocking your FSB you might cause pretty bad instability. 4 is probably the safe setting, and probably offers the best performance/stability ratio. Also, it may be the case that a burst length of 8 is higher than most applications demand. If you're not gaming or running memory-intensive apps, you probably wouldn't see a difference until you had a random crash.

8 might also be a waste of time on a multitasking system that reads from different rows of memory constantly, or it might be wasteful if the system forces itself to wait 8 ticks before it does anythng else (adding in possible latency), but those both seem unlikely to me.

 

Thanx Chicken, I guess there's a reason for Burst-Length coming up as "4" when SPD is enabled.
BTW - Thanx, whoever posted this:


Windows 2k/XP Stop Error and Bug Check Codes:
http://msdn.microsoft.com/library/e..._f55acfed-3296-4e84-8885-c3162fd0ddbf.xml.asp