2.MemOK! button

Installing DIMMs that are not compatible with the motherboard may cause system boot failure, and the DRAM_LED near the MemOK! switch lights continuously. Press and hold the MemOK! button until the DRAM_LED starts blinking to begin automatic memory compatibility tuning for successful boot.

•Refer����� to�� section������� 1.2.8 Onboard LEDs for the exact location of the DRAM_LED.

•The��� DRAM��������LED also���� lights������ up�� 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 fails����� ��to ����boot up�� ���due ��to BIOS���� �������������overclocking, press����� ���the ������MemOK! switch������

to boot and load the 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.

Chapter 1

ASUS M5A99FX PRO R2.0

1-25