We could have stopped right here, if it hadn’t been for one thing. The new BIOS version 0404 provided the ability to manually adjust Strap frequency that can now be set to Auto, 200, 266 and 333MHz.

However even this function doesn’t show us for sure if the performance remains unchanged during Strap changing. The thing is that the list of available memory frequency dividers depends on the selected FSB Strap value. Moreover, the ranges of available dividers at different Strap settings do not overlap.

This allows us to conclude that FSB Strap frequency on Asus P5K Deluxe is connected to the set divider forming the memory frequency. In other words, Strap is changed only when the memory frequency divider changes. That is why we didn’t notice Strap changing in our tests, because it occurred when we corrected the testbed parameters – selected a different memory frequency divider and reduced the processor clock frequency multiplier.

So, it turns out that Asus P5K Deluxe doesn’t have any set boundaries for Strap changing, placing full responsibility for it on the user who can either set it directly or through memory frequency. Unfortunately, for the same very reason we cannot compare the mainboard performance with different Strap settings.

However, we shouldn’t forget that FSB Strap frequency is not really that interesting as is, but bears huge auxiliary importance. Strap is the FSB frequency limit after which overclocking doesn't lead to a significant performance boost. Therefore we decided to carry out one more test: to analyze the performance of systems with the CPUs overclocked to the same speeds but using different multipliers and FSB frequencies. By comparing these results we will be able to find the most “optimal” FSB frequencies for successful overclocking.

The obtained results are given in the table below. The CPU in these tests worked at 3.2GHz. The memory frequency was set as close to 1066MHz as possible. The timings were locked at 4-4-4-12-8-30-8-8-8. Transaction Booster was set to Auto, and DRAM Static Read Control – to Enabled.

Actually, we didn’t expect anything else. Higher FSB frequency on Asus P5K Deluxe always leads to higher performance, independent of the memory frequency dividers and FSB Strap. So, this mainboard has no hidden issues such as unpleasant performance drops occurring once you get beyond certain FSB frequencies.

In conclusion to our extensive discussion I would like to say a few words to those Asus P5K Deluxe owners who for some reason believe that it changes FSB Strap at 500MHz. In reality there is no Strap changing whatsoever and cannot be. All tests that allegedly prove this statement haven’t been performed correctly. The thing is that if the DRAM Static Read Control parameter is set to Auto, the mainboard changes its value at this frequency. That is why the performance drops, which is erroneously considered to be caused by Strap changing. To eliminate this unpleasant effect, you should set DRAM Static Read Control to Enabled in the BIOS Setup.