AM2 Motherboards-Part 4: ATI Crossfire Xpress 3200

Overclocking

MSI K9A Platinum Overclocking Testbed
Processor:	AM2 4800+ (X2 2.4GHz 1MB L2 Cache per core)
CPU Voltage:	1.525V (default 1.4V)
Cooling:	AMD Stock Heatpipe FX62 Cooler
Power Supply:	OCZ Power Stream 520W
Memory:	Corsair Twin2x2048-PC2-8500C5 (2x1GB) (Micron Memory Chips)
Hard Drive	Hitachi 250GB 7200RPM SATA2 16MB Cache
Maximum OC: (Standard Ratio)	258x12 (Normal, 3-3-3-13) 3096MHz (+29%)
Maximum FSB: (Lower Ratio)	335 x 9 (For Overclocking, 3-3-3-13) (3015MHz, 2 DIMMs in DC mode) (+68% Bus Overclock)

MSI reached one of the higher overclocks in our roundup, topping out at 335x9. At stock 12x the board maxed out at 258. Both of these are a bit lower than the ASUS with its 8-phase power regulation, but results are still remarkably close to the ASUS considering this is a cheaper board and a much simpler design. Most of the credit for the overclocking performance should go to the ATI RD580 chipset. The K9A was very stable at the fastest 335 speed. Perhaps just as important, the MSI recovered gracefully from bad overclocks - allowing a reboot and entry into the BIOS to fix the settings from a bad OC.

Memory Testing
Optimum tRAS

DDR2 memory behaved a little differently in RD580 tRAS testing than we have seen on other AM2 boards. As you can see from the standard chart below, a 2GB kit of Corsair 8500 (DDR2-1066) achieved the best bandwidth at tRAS settings of 12 to 14. As a result we used 13 as our tRAS setting for all benchmarking.

Memtest86 Bandwidth MSI K9A Platinum with AM2 4800+
6 tRAS	2047
7 tRAS	2047
8 tRAS	2047
9 tRAS	2093
10 tRAS	2093
11 tRAS	2141
12 tRAS	2192
13 tRAS	2192
14 tRAS	2192
15 tRAS	2047
16 tRAS	2047
17 tRAS	2047

Since the optimum tRAS timing seems to vary with DDR2 depending on chipset, motherboard, and CPU, the best way to achieve maximum bandwidth with any configuration is to run your own series of tRAS timing tests with MemTest86, which is a free program. It only takes a few minutes to find out what works best for your individual configuration.

Memory Stress Testing

The MSI K9A supported a wide enough range of memory voltages and timings to allow memory stress testing at 3-3-3-13 timings at DDR2-800. This has become our standard test setup for Socket AM2 and Core 2 Duo memory testing. This is mainly because these aggressive timings at DDR2-800 almost always yield the best overall performance on these two processors. Conroe may be a little faster at aggressive DDR2-1066 timings, but AM2 does not normally support DDR2-1067, leaving DDR2-800 as the highest performing common memory speed.

As found in our Conroe Buying Guide: Feeding the Monster, most DDR2-800 memory is rated at conservative 5-5-5-15 timings, because that assumes you only run with the default 1.8 V DDR2 voltage. We have found in our DDR2 testing that many modules are easily able to run 4-4-4-12 timings at 2.0 V, and most high-end modules like the Corsair modules we are using for benchmarking (rated at 5-5-5-18 DDR2-1066) are generally able to run with 3-3-3 timings at DDR2-800 and approximately 2.2V. Even value ram based on Elpida memory chips can manage 4-3-3 timings at DDR2-800 with 2.2V to 2.3V memory voltage.

MSI K9A Platinum DDR2-800 Timings - 2 DIMMs (2/4 slots populated - 1 Dual-Channel Bank)
Clock Speed:	200MHz
Timing Mode:	800MHz - Default
CAS Latency:	3
RAS to CAS Delay:	3
RAS Precharge:	3
RAS Cycle Time:	13
Command Rate:	1T
Voltage:	2.3V (2.2V with 2T)

With two DIMMs installed, testing was completely stable at 3-3-3-13 1T timings at DDR2-800. This is very rare since AMD does not really support 1T timings in the current on-chip memory controller. However, MSI joins Gigabyte and ASUS as the only AM2 boards to support Command Rate 1 at DDR2-800. We did find, with the Auto or 2T setting, that stability could be achieved at a lower 2.2V setting. This is important to know when trying to squeeze the most from motherboards with limited memory voltage options.

Several benchmarks were run to compare performance at 1T and 2T timings. As in past testing, we could not find any real-world performance improvements with the 1T timings compared to 2T. This will likely remain the case until AMD releases a new AM2 memory controller that will officially support 1T Command Rate.

MSI K9A Platinum DDR2-800 Timings - 4 DIMMs (4/4 slots populated - 2 Dual-Channel Banks)
Clock Speed:	200MHz
Timing Mode:	800MHz - Default
CAS Latency:	3
RAS to CAS Delay:	3
RAS Precharge:	3
RAS Cycle Time:	13
Command Rate:	2T
Voltage:	2.3V

Installing four DIMMs stresses the memory subsystem further, but the MSI K9A did handle 4 DIMMs at the same timings and a 2T command rate. While the system was stable at the same 3-3-3-13 timings that worked best with 2 DIMMs we needed to adjust to the top of the available voltage options and did wish we had a bit more DIMM voltage.

The MSI and ASUS are the only AM2 motherboards we have tested so far that are able to run 4 1GB DIMMs at 3-3-3 timings. That performance speaks very well for the stability of both designs, since the memory controller in all our motherboard tests is the same initial release AM2 CPU.