DFI X48 LT T2R: Floats like a Butterfly…

Still on our feet (BIOS)

Using AUTO for all sub-timings is generally acceptable until we start pushing for every last MHz of bandwidth and latency. The BIOS defaults are generally tight enough for reasonable performance on 24/7 PCs. We used Memset while running Windows XP to check where the AUTO DRAM timing defaults set the memory parameters. The timings shown by Memset were noted by us and entered manually into the relevant BIOS functions. We then began to tighten these values one at a time, noting the effects of any changes on bandwidth, latency, and stability. For benchmarking, we tend to use Memset once the XP operating system has loaded rather than entering overly tight settings directly in the BIOS. We can then begin to tighten the sub-timings far beyond 24/7 settings.

Additional Setting Ranges:

Ref to Act Delay (TRFC): The range of use for 1GB modules in 2GB setups is anywhere from 20-40 depending on overall memory speed. Lower values are more aggressive and give boosts in Read Bandwidth. For double density (2GB) modules, a higher tRFC range is required. For 4GB of memory running up to 1100 MHz, a value of 42 and above is usually required (54 is more compatible). For 8GB of memory a minimum value of 54 should be used.

MCH ODT Latency: ODT (On Die Termination) is used to match the MCH output impedance to the termination resistance of the RAM. Use of 1-2 is fine in most cases. Even for 4GB overclocking we did not find that more than a setting of 1 was required.

Write to PRE Delay (tWR): Range is from 10-13. For high RAM speed, use 12 and above for stability; for benchmarking 10-12 will be faster. Lower is faster.

Rank Write to Read (tWTR): Range is 9-11. Use 11 for stability and 10 or 9 for benchmarking. Lower is faster.

ACT to ACT Delay (tRRD): Range is 2-5. 3 is a good setting that allows high enough FSBs for most users. Higher numbers result in less memory read performance.

Read to Write Delay (tRDWR): Range is 8-9. 8 is ideal for most users; higher values are slower.

Ranks Write to Write (tWRWR): AUTO

Ranks Read to Read (tRDRD): AUTO

Ranks Write to Read (tWRRD): AUTO

The ranges for all these settings are quite well manipulated by SPD and BIOS. For those wishing to experiment, 4 is the lowest and most aggressive setting. 5-4-5 may work for SuperPi type benching. There is a slight write/copy speed increase with tighter settings, but this is only useful for extracting the last ounce of performance. For stability these are best left on AUTO

Read CAS# Precharge (tRTP): 2-3 works well on this board for most users. 2 is used for benchmarking while 3 and upwards are best for stability.

ALL PRE to Refresh: Range is 4-5. A setting of 4 is fine for most benchmarking, unless shooting high over 500FSB.