FSB Strap

Besides the influence Command rate and Transaction Booster settings have on the system performance, we also paid special attention to the FSB frequency when Asus P5K Deluxe changed Strap and the resulting performance drop. For instance, Asus mainboards on iP965 chipset start changing strap at 401MHz FSB, which leads to noticeable performance drop when we hit the corresponding frequency during overclocking.

In order to find out what the situation looks like on Asus P5K Deluxe mainboard, we tested the memory subsystem performance with the FSB frequency increment of 10MHz. the memory frequency in this session was set with the 4:5 FSB:Mem divider (this is the minimal divider available in the entire FSB frequency range). The CPU clock frequency multiplier was set to 8x. The memory timings were set manually at 5-5-5-15-11-42-10-10-10, so that the memory could work stably at maximum frequencies. Transaction Booster was set to Auto, DRAM Static Read Control – to Disabled. The obtained results are given in the table and on the diagrams below:

Up to 460MHz FSB the performance is growing more or less gradually. If we disregard the unexplainable speed upsurge at 320MHz FSB, we can state that the memory subsystem performance is growing almost linearly within 266MHz-460MHz FSB frequency range. In other words, there is simply no Strap changing in this interval, or it occurs without any visible changes in the mainboard performance.

To check out that there are no performance drops during further increase in the FSB speed, we continued the performance test of the memory controller. Of course, in order to get to higher FSB frequencies we had to reduce the processor clock frequency multiplier down to 7x and set the front side bus and memory bus to synchronous clocking mode. Other settings remained unchanged.

We don’t see any performance drops here either. The memory controller performance results form an almost ideal straight line. So, Asus P5K Deluxe appears the first mainboard that doesn’t suffer from negative effects of the FSB Strap changing on performance.