As AMD constantly adjusts its Athlon64 processor prices, the popularity of Socket939 Athlon64 supported in dual-channel memory is increasingly high. Some users have purchased them. I believe there are many of them to experience its super-memory bandwidth. So how do you set up to make the Athlon64 platform get the best memory performance? It is well known that the memory controller of the K8 platform is not on the motherboard chip, but is integrated into the CPU to minimize delay. But this also makes it a high quality and matching of memory. Among them, Socket939 Athlon64 is even. How do you solve this problem? AMD uses the "sacrificial speed exchange stability" method, which introduces control of memory Command Rate in the memory controller. Control, referred to as CMD Rate). The meaning of this parameter is to give a specific addressable line of streaming command after selecting the physical bank, and is in units of clock cycles. Usually we see some memory delay information, you will see memory parameters to write: CAS 2.5-3-3-7-1T. The four numbers in front are we discussed more memory CL (column address pulse reaction time), TRCD (RAS to CAS delay), TRP (row precharge time), TRAS (row address pulse response time). "1T" is the parameter of Command Rate. Generally we can also see "2T", 2T delay is longer than 1T. Command Rate is not a new thing, but it is difficult to see the relevant options in the previous motherboard BIOS. Memory Command Rate Working Status We can view (Figure 1) with EVEREST. Press AMD, when the memory module uses 1T TIMING and CPU Overseofrection Synchronization to get the best Memory performance. However, when the memory module in the motherboard increases, the load of the memory controller will increase, and the command interval may affect memory stability. If instability occurs, AMD recommends that the user will be set to 2T Timing. Now most K8 motherboards have related options, users can regulate themselves. As can be seen from Command Rate, the setting of the Command Rate parameter is also related to the number of memory Bank. The partial chipset of Intel limits the maximum memory BANK number of memory channels to 4 so that 1t Timing can be used. In the two-channel K8 platform, if the user is loaded in the two memory channels in the two memory channels, the number is not equal (such as single double-sided memory mix, inserting three memory, etc., this is called an asymmetric dual channel), then the CPU will Set the Command Rate to default to 2T, and even the memory is down. When all of the DIMM slots on the motherboard are filled, even if the number of BANKs, only 2T Timing can be used. So the user must pay attention to the matching of memory. This is not "motherboard picking up" and cannot be solved by replacing the motherboard. So how much is 1T and 2T impact on system performance? We can use tests.
Test platform: CPU: Athlon64 3200 (939) Motherboard: MSI K8N Neo2-Platinum (nForce3 Ultra) memory: Kingston Hyperx PC3200UL 256MB × 2 A-DATA VITESTA DDR400 256MB × 2 graphics card: Inno3D GeForce 6800GT 256MB GDDR3 hard drive: Mai Tuojin Drill nine generation 120g PATA / 2M Power: All Han FSP400-60THN-P (Rated Power 400W) System and Drive: WindowsXP SP2, NVIDIA ForceWare 71.24WHQL, NVIDIA ForceWare 6.14Beta (Chipset Driver) MSI K8N NEO2-Platinum motherboard pair memory Command Rate Time Options "1T / 2T Memory Timing" has 1T, 2T, Auto three gears. When set to Auto, the Command Rate delay will be determined by the memory controller. Kingston Hyperx PC3200UL is double-sided memory, using Samsung -TCCD particles. The A-DATA ViteSTA DDR400 is single-sided memory, which uses PowerCHIP particles. Default frequency test memory SiSoft Sandra 2004 SP2B 3DMARK03 HYPERX UL DDR400 × 22-2-2-5-1T INT 6035MB / SFLOAT 6044MB / S 11341 Hyperx UL DDR400 × 22-2-5-2T INT 5341MB / SFLOAT 5339MB / S 10940 Vitesta DDR400 × 22.5-3-3-7-1T INT 6008MB / SFLOAT 5991MB / S 11309 When the memory of the same frequency and the CL value is working in 2T Timing, the memory bandwidth measured by SiSoft Sandra 2004 Memry Benchmark is working 1T Timing is less than 700MB / s. Just adjust a parameter of memory, performance is so big, it is really amazed. Although 3DMARK03 score is not particularly sensitive to CPU and memory, this gap has brought 400 points to the last results. Although Vitesta DDR400's CL delays are higher than Hyperx UL, it has far from test results. Not 2T Timing. Overclocking Test Memory CPU Word SISOFT SANDRA 2004 SP2B 3DMARK03 Hyperx UL DDR540 × 22.5-3-3-9-1T 9 × 270.1 = 2430.9 MHz INT 7406MB / SFLOAT 7406MB / S 11768 Hyperx UL DDR604 × 23- 4-4-8-2T 8 × 302.8 = 2422.4MHz INT 6848MB / SFLOAT 6849MB / S 11544 Vitesta DDR466 × 22.5-4-4-8-1T 10 × 233.3 = 2333 MHz INT 6779MB / SFLOAT 6788MB / S 11469 Because Athlon64 has Reduce the ability of the multiplier, which can be highly added to the memory frequency without changing the CPU. The same is the same as the parameters such as the CL value. The hand in the hands of Kedton Hyperx UL has CL = 2.5, and the memory voltage can reach 270 MHz-1T (equivalent DDR540, Hypertransport bus double) (Fig. 2, Figure 3).
