Asus A8R32-MVP Deluxe: First ATI RD580

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.