Asus X99-E-10G WS User Manual page 34

3. DRAM LED (DRAM_LED)
The DRAM LED checks DRAM during motherboard booting process. If an error is
found, the LED flashes until the problem is solved.
4. USB BIOS Flashback LED (FLBK_LED)
The BIOS Flashback LED flashes when you press the BIOS Flashback button for BIOS
update.
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Chapter 1: Product Introduction