While it’s supposed to be their budget X58 motherboard, ASUS provides a wealth of options for tweaking the P6T inside BIOS. In fact, its BIOS offerings are pretty comparable with the P6T Deluxe. As a result, if you’re already familiar with the P6T Deluxe’s BIOS, you may as well just skip to the next section, as functionality between the P6T Deluxe and P6T is similar.
As usual with ASUS motherboards, most of the BIOS settings you’ll want can be found in AI Tweaker section of BIOS. Here you’ll find BIOS settings for clock multiplier adjustment, base clock frequencies, PCIe frequency, memory frequency, etc, etc.
In terms of base clock (bclk) speeds available, ASUS provides settings ranging from 100-500MHz in 1MHz increments. If you’d prefer to simply type in your bclk speed manually, you can do that too. DRAM speeds of 800MHz and 1066MHz are the only settings provided for Core i7-920 and 940; you’ll need an Extreme Edition CPU to unlock memory speeds of 1333MHz, 1600MHz, 1800MHz, 1866MHz, and 2133MHz.
Of course, these settings are simply memory multipliers that are tied to the current bclk setting, so as you crank up the base clock, the memory speeds will go higher as well. When an Extreme Edition CPU is installed, the uncore clock ratio (uclk) and QPI link data rate settings are also adjustable in BIOS, and finally, PCIe speeds range between 100-200MHz in 1MHz increments.
This is the exact same functionality ASUS provides on the more expensive P6T Deluxe.
In terms of voltages, once again the BIOS settings are similar to the P6T Deluxe. One thing we should also note here is that the voltage selections available in BIOS for key settings such as CPU voltage, QPI/DRAM core voltage, and DRAM voltage, are variable depending on jumpers.
In other words, ASUS provides additional voltage options in BIOS for these key settings if you’re willing to pull some jumpers located on the motherboard. The default settings provided inside BIOS are more than enough for 95% of users who would like to OC their processor, but that 5% who will be using extreme cooling measures such as liquid nitrogen will want to use the jumpers to expose the additional voltage options hidden inside the P6T’s BIOS.
Again, this is the same system ASUS employed with the P6T Deluxe.
By default, CPU voltages provided inside the P6T BIOS range from 0.85V-1.7V in increments of 0.00625V. Once the OV_CPU jumper is enabled though, the max voltage goes up to 2.1V. CPU PLL voltage values range from 1.8V-2.50V with a 0.02V interval.
For adjusting QPI link voltage, options range from 1.20V-1.70V by default; once the OV_QPI_DRAM jumper is enabled, that ceiling climbs to 1.90V.
Chipset voltages are also adjustable. IOH voltages range from 1.10-1.70V in 0.02V increments, while the IOH PCIe voltage settings range from 1.50V-2.76V in 0.02V increments. For the South Bridge, ICH voltages range from 1.10V-1.40 with a 0.10V interval, while ICH PCIe voltage range from 1.50V-1.80V in increments of 0.10V.
For memory OC’ing, DRAM voltages range from 1.50V-1.90V in 0.02V increments. Here again ASUS provides additional voltages if you enable the OV_DRAM_BUS jumper. Once this jumper is set to on voltage options go up to 2.46V. Here we should note that unlike previous Intel CPUs, starting with Nehalem Intel states that memory voltages beyond 1.65V could potentially damage the processor. So if you’re going to crank up the memory voltage to a really high level, you’ll want to ensure that the processor has very good cooling. For even further fine tuning of memory voltages, the P6T provides settings for adjusting DRAM data and control reference voltages on all three channels of the memory controller. Values range from 0.395x to 0.630x with a 0.005x increments. According to ASUS, adjusting these ratios may enhance DRAM overclocking ability.
ASUS also provides BIOS settings for adjusting CPU VDroop directly as well as CPU differential amplitude, IOH clock skew, and CPU clock skew. These settings are provided in order to enhance bclk overclocking.
Like previous ASUS motherboards, the P6T BIOS also provides Q-Fan settings for adjusting CPU/system fan speeds by predetermined amounts, as well as the ability to save BIOS profiles, which is helpful if you’d like to run different OC’ing settings for certain games (say for instance, your system can run Far Cry 2 OC’ed at 4.0GHz with complete stability, but you need to dial it down to 3.95GHz for Crysis) or underclocking.
So how far did we manage to OC our P6T motherboard? How does 210MHz sound! We were able to run our looped Far Cry 2 stability tests at this speed, but when we attempted the looped 3DMark Vantage run the system crashed. We think this was caused by excessive temperature, but even with repeated attempts to resolve the problem stability was iffy (for the record we used a Thermalright Ultra-120 eXtreme 1366 CPU cooler for all our testing). By the time we mounted additional system fans to the motherboard and were ready to boot back up for another stab at the Far Cry 2+3DMark Vantage looped combo, the system BSOD’ed shortly after the Windows Vista splash screen came up. At this point we had to give up so we could bring you an article today.
Ultimately in order to achieve complete 100% stability we had to settle for a base clock frequency of 197MHz. Not shabby at all for a $250 motherboard!