ASUS F2A55 User Manual

Installing DIMMs that are incompatible with the motherboard may cause system boot failure, 

and the DRAM_LED near the MemOK! switch lights continuously. Press and hold the 

MemOK! switch until the DRAM_LED starts blinking to begin automatic memory compatibility 

tuning for successful boot.

• 

Refer to section 1.10 Onboard LEDs for the exact location of the DRAM_LED.

• 

The DRAM_LED also lights when the DIMM is not properly installed. Turn off the 

system and reinstall the DIMM before using the MemOK! function.

• 

The MemOK! switch does not function under Windows

®

 OS environment.

• 

During the tuning process, the system loads and tests failsafe memory settings. It 

takes about 30 seconds for the system to test one set of failsafe settings. If the test 

fails, the system reboots and test the next set of failsafe settings. The blinking speed 

of the DRAM_LED increases, indicating different test processes.

• 

Due to memory tuning requirement, the system automatically reboots when each 

timing set is tested. If the installed DIMMs still fail to boot after the whole tuning 

process, the DRAM_LED lights continuously. Replace the DIMMs with ones 

recommended in the Memory QVL (Qualified Vendors Lists) in this user manual or on 

the ASUS website at www.asus.com.

• 

If you turn off the computer and replace DIMMs during the tuning process, the system 

continues memory tuning after turning on the computer. To stop memory tuning, turn 

off the computer and unplug the power cord for about 5–10 seconds.

• 

If your system fail to boot due to BIOS overclocking, press the MemOK! switch to boot 

and load BIOS default settings. A message will appear during POST reminding you 

that the BIOS has been restored to its default settings.

• 

We recommend that you download and update to the latest BIOS version from the 

ASUS website at www.asus.com after using the MemOK! function.

Onboard switches allow you to fine-tune performance when working on a bare or open-case
system. This is ideal for overclockers and gamers who continually change settings to 

enhance system performance.

ASUS F2A55

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