The BIOS of the ASUS M2n-SLI Deluxe is based on the Award microcode and offers good overclocking opportunities, particularly:
- Adjusting the clock-generator frequency from 200MHz to 400MHz stepping 1MHz
- Adjusting the PCI Express bus frequency from 100 to 200MHz stepping 1MHz
- Changing the DDR2 SDRAM voltage from 1.8 to 2.5V stepping 0.05V
- Changing the CPU voltage from 0.8 to 1.5625V stepping 0.0125V
- Changing the CPU multiplier with a step of 1
Note the very high top limit of the memory voltage. In the earlier versions of the BIOS the multiplier could be adjusted with a step of 0.5.
Besides that, the Advanced Voltage Control section gives you the following options to control the mainboard’s voltages:
- CPU/Chipset HT Voltage: 1.2-1.5V stepping 0.05V
- Chipset Core Voltage: 1.4-1.6V stepping 0.1V
- Chipset Standby Core Voltage: 1.4V or 1.6V
- Chipset PCI Express Voltage: 1.5-1.7V stepping 0.05V
- CPU VCore Offset Voltage: Disabled, 100mV offset
As for the memory timings, the list of adjustable parameters is very long and would take several pages to write down.
The testbed was configured like follows:
- AMD Athlon 64 3000+ CPU (1.8GHz, Orleans F2, Socket AM2)
- Asus M2N-SLI Deluxe mainboard (Nvidia nForce 570 SLI chipset), rev 1.01G, BIOS 0304
- Corsair TWIN2X1024-8000UL DDR2 SDRAM
- Chaintech GeForce 7900 GTX graphics card (24p/8v, 650/1600MHz)
- Western Digital Raptor WD740GD hard disk drive
- Corsair Nautilus500 cooling system
- Thermal paste from Zalman
- Sunbeamtech Nuuo SUNNU550-EUAP power supply (550W)
- Windows XP SP2
I took an AMD Athlon 64 3000+ processor for my tests. At its default voltage it is known to be able to work at a clock-generator frequency of 300MHz, i.e. at a clock rate of 2.7GHz. If the voltage is increased to 1.5V, this CPU is stable at 320MHz clock-generator frequency (2.88GHz clock rate).
Having reduced the memory and HyperTransport frequencies, I tried to start up at a clock-generator frequency of 300MHz, but the mainboard hung up during the POST right after detecting the memory modules. I thought there might be a problem with the BIOS, so I updated it from version 0202 to the newest 0304 and set the clock-generator frequency at 280MHz. The mainboard started up normally and booted the OS and passed a few tests. But when I restarted the computer, the system hung up. On the restart it issued the standard message that the CPU had been over-overclocked and invited me into the BIOS Setup. I thought the mainboard just lacked a bit of stability and reduced the clock-generator frequency by only 5MHz. But then I had to reduce it by 5MHz more, then by 10MHz more, etc.
In every case the system booted up normally, but always hung up on restart. It only became stable at a clock-generator frequency of 220MHz, i.e. a mere 10% above the default.