To clear out the situation somewhat, we carried out a testing session with an ASUS P4P800-E Deluxe and DDR500/DDR533 SDRAM. The testbed included an ATI RADEON 9800XT graphics card and an Intel Pentium 4 3.4GHz CPU (Northwood core). The Corsair CMX512-3200LLPro memory we use in the current testbed doesn’t allow enabling the Performance Mode at 200MHz FSB, so we also publish results for 201MHz FSB at which frequency the mainboard is less finical about the memory as in the Turbo mode. The Memory Acceleration Mode was enabled in all cases. OCZ PC4200 Enhanced Latency was used as DDR500 and DDR533. We disabled the Performance Mode altogether when testing DDR500 and DDR533, because otherwise their performance degenerated.

We’ve got funny results. It turns out that the use of dual-channel DDR533 or DDR500 at 200MHz FSB does make sense. That is, you can achieve better results with DDR400 SDRAM, but only if you also enable the Performance Mode, but you need support of 2-2-2-5 timings for that! Not all memory modules are operational at such timings. Note also the following fact: there’s no sense in increasing the FSB clock rate to 201MHz to set the Performance Mode option to Turbo (it is possible for any memory modules and timings if the FSB frequency is other than 200MHz). At 200MHz FSB, the mainboard automatically enables certain additional optimizations, missing at other FSB clock rates. Thus, setting a FSB clock rate different than 200MHz you will see the performance degenerating, in spite of your setting the Performance Mode to Turbo!

Thus, the ASUS P4P800-E Deluxe mainboard seems to have three kinds of optimizations for the memory subsystem:

• Memory Acceleration Mode, enabled in the BIOS Setup, works with nearly every memory module and provides a slightly higher performance;
• Performance Mode gives a positive effect only with 200MHz FSB and requires that the memory modules were stable with 2-2-2-5 timings at such FSB clock rate. By setting the Performance Mode option to “Turbo”, you reach noticeable performance gains;
• Optimizations that the mainboard enables automatically at 200MHz FSB, without putting any restrictions on the memory modules. These optimizations provide the highest performance growth.

In short, from the point of view of the maximum performance, you should use the mainboard with 200MHz FSB, even though you don’t set the Performance Mode to Turbo.

Now that we’ve dealt with memory, let’s move on to overclocking options. ASUS traditionally pays much attention to the overclockability of its products. The P4P800-E Deluxe is no exception to the rule. The Setup offers an abundance of overclocking-related settings, which are all gathered in the JumperFree Configuration page:

When releasing its i875/i865-based mainboard series, ASUS announced the new AI Overclocking technology for speeding the system up by 30% (this depends on the CPU and memory used) without any effort. This technology shows itself as options like Overclock 5%...Overclock 30% in the BIOS Setup, which simply increase the FSB clock rate by the appropriate percent. It is of little interest to us, so we recommend setting the AI Overclock Tuner option to Manual and get the full access to all overclocking settings. They include:

• Adjustment of the FSB frequency. The formal range stretches from 100 to 400MHz;
• The AGP/PCI busses can be clocked independently: Auto, 66.66/33.33MHz, 72.73/36.36MHz, and 80.00/40.00MHz. Thus, you can just fix the AGP/PCI frequencies and don’t worry about them at FSB-overclocking;
• Control over the CPU voltage. The Vcore can be raised from the nominal CPU voltage to 1.9v stepping 0.025v. That’s flexible enough;
• Control over the memory voltage. The Vmem can be set to Auto, 2.55v, 2.65v, 2.75v and 2.85v;
• Control over the AGP voltage. The Vagp is adjustable from 1.5v to 1.8v stepping 0.1v;
• You can change the ratio of the memory clock rate to the FSB one. At over 200MHz FSB, the following FSB:Mem ratios are available: 3:2, 5:4, 1:1, 4:5, and 3:4.

For comfortable overclocking, ASUS claims support of the CPU Parameters Recall technology: if the system doesn’t start up after your changes in the BIOS Setup, you can roll the settings back to their defaults by pressing and holding the INS key when powering the mainboard on. This way you can get into the BIOS Setup at the “safe” settings and correct the wrong parameters.

Overall, the P4P800-E Deluxe offers good opportunities for non-extreme overclocking. In fact, its overclocking options haven’t changed since the ASUS P4P800 Deluxe. Well, this also needs proving in practice.