Optimum tRAS
In past reviews, memory bandwidth tests established that a tRAS setting
of 11 or 12 was generally best for nForce2, a tRAS of 10 was optimal
for the nForce3 chipset, a tRAS of 7 was optimal for the nForce4/ATI
RD480/ULi M1697 chipsets, and a tRAS of 10 produced the best bandwidth
on the ULi 1695.
Since this is our first review of a board with the new ATI RD580
chipset, tRAS timings were first tested with memtest86, a free
diagnostic program with its own boot OS that will boot from either a
floppy disk or optical disk. Bandwidth of OCZ PC3200 Platinum Rev. 2, based on Samsung TCCD chips, was measured from tRAS 5 to tRAS 15 to determine the best setting.
Memtest86 Bandwidth Asus A8R32-MVP with Athlon 64 4000+ |
5 tRAS |
1879 |
6 tRAS |
1879 |
7 tRAS |
1999 |
8 tRAS |
2043 |
9 tRAS |
1999 |
10 tRAS |
1958 |
11 tRAS |
1958 |
12 tRAS |
1879 |
13 tRAS |
1870 |
14 tRAS |
1843 |
15 tRAS |
1807 |
The tRAS setting that produced the highest memory bandwidth with the
ATI RD580 chipset was 8. The tRas 8 setting was used for all memory
testing on the Asus A8R32-MVP Deluxe.
Memory Stress Testing
The Asus A8R32-MVP easily handles 2-2-2-8-1T timings at stock speed.
The default setting for Command Rate in the Asus BIOS is 1T, which
makes it much easier to assure that the A8R32-MVP consistently delivers
top performance than the 2T default seen in the earlier A8R-MVP. We are
pleased that Asus decided to implement the more sensible 1T timings in
the update to the A8R-MVP.
Running four double-sided 512MB or 1GB DIMMs is much more demanding
than running two DS DIMMs, and Asus did not have any special magic
here. Like every board that we have tested, except the DFI RDX200, we
needed to drop the Command Rate to 2T with 4 DS DIMMs. This really
should not be a surprise, since the DIMM timing is primarily a function
of the memory controller on the AMD processor. With 4 DIMMs, the
A8R32-MVP remained stable with the same aggressive 2-2-2-8 timings that
worked best for two DS DIMMs.
Stable DDR400 Timings - 4 DIMMs (4/4 DIMMs populated) |
Clock Speed: |
200MHz |
CAS Latency: |
2.0 |
RAS to CAS Delay: |
2T |
RAS Precharge: |
8T* |
Precharge Delay: |
2T |
Command Rate: |
2T |
*8T was determined by MemTest86 benchmarks to
deliver the widest bandwidth with the ATI RD580 chipset. While the
board would operate at tRAS of 5T or lower all benchmarks were run at
8T.

February 17, 2006
February 16, 2006
February 15, 2006