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What are the canonical meanings of the different DRAM_LED, power button and beep patterns prior to BIOS POST on Asus motherboards? My manual and miscellaneous web searches have turned up nothing but vague notions in forums.

My specific issue is that after changing the PSU (the old one didn't die, but had a power button issue) to a Corsair AX760 and connecting only the CPU and 24 pin motherboard cables:

  • the power button on my ASUS P6X58D-E motherboard always stays red when power is on,
  • the fans start up,
  • DRAM_LED stays lit, and
  • the speaker plays a nerve-shattering single continuous beep.

After pressing the MemOK! button

  1. the computer restarts,
  2. the continuous beep continues, and
  3. DRAM_LED lights up three times then goes dark.

I've tried pressing the MemOK! button with miscellaneous configurations of memory (1st, 2nd and 3rd slot), and sometimes get three blinks, sometimes two and sometimes one. Having a reference for all of these would be extremely useful.

If I attach any other cables to the PSU (SATA, GPU) the power button stays red but doesn't do anything. That is, if I press it there's no beep, DRAM_LED light or fans running.

It should not be a power problem, since the new PSU has more wattage than the old one, and it's running the same hardware. The 24+8 motherboard+CPU connectors are all connected.

Update: After switching to the cables provided with the PSU I am now able to boot. Who knows why? Unfortunately it looks like one SSD and one HDD were fried by dust shorts in the process - The SSD is not detected and the machine refuses to start if I connect the power plug to the HDD (I tried multiple cables). In any case, the original question still stands - how do you interpret the patterns?

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This doesn't answer your specific question, but it almost sounds like the new PSU doesn't have enough juice to start everything up. Does your motherboard have the 24+8 power connector? That might be the issue as well if you don't have the extra 8-pin connector hooked up. –  Taegost Jul 10 '13 at 18:25
@l0b0 See the update to my answer. The DRAM led lights up when the Motherboard is trying to boot with untested ram. –  spuder Jul 31 '13 at 19:21
The manual has the answer "...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." –  spuder Jul 31 '13 at 19:40

1 Answer 1

up vote 5 down vote accepted

You state:

Update: After switching to the cables provided with the PSU I am now able to boot. Who knows why?

It sounds like you had a modular power supply, and you new power supply is also modular. Did you leave the cables from the older power supply in place?

Modular cables are not interchangeable! Most use the same 6 pin connectors to connect to the PSU, but have completely arbitrary pinouts which vary depending on the vendor.

Take a close look at the old cables and the new cables. I'll bet the wires coming out of the ends are in a different arrangement. The fact that you lost 2 hard drives makes me even more sure that this is a reverse polarity issue, not dust shorts.

The P6X58D-E uses an AMI bios, here are the beep codes.

1 short DRAM refresh failure  
2 short Parity circuit failure  
3 short Base 64K RAM failure  
4 short System timer failure  
5 short Process failure  
6 short Keyboard controller Gate A20 error  
7 short Virtual mode exception error  
8 short Display memory Read/Write test failure  
9 short ROM BIOS checksum failure  
10 short    CMOS shutdown Read/Write error  
11 short    Cache Memory error  
1 long, 3 short Conventional/Extended memory failure  
1 long, 8 short Display/Retrace test failed  


Asus motherboards have a built in memory tester called DMEM OK. They have posted a video to their youtube page which demonstrates how to use the memory tester. https://www.youtube.com/watch?v=9azllBzU5PU

In the video you will notice that the machine is not booting. They press the DMEM OK button and the DRAM_LED starts flashing. The flashing means that the motherboard is testing the ram. The blinking is not intended to be user readable.

The Manual for your motherboard states:

Memory compatibility is among the top concerns during computer upgrades. Worry no more. MemOK! is the fastest memory booting solution today. This remarkable memory rescue tool requires nothing but a push of a buttton to patch memory issues and get your system up and running in no time. The technology is able to determine failsafe settings that can dramatically improve your system booting success. Refer to page 2-24 for details.

It is most assuredly testing different latencies of the ram until it finds one that works, the led is simply there to let you know it is testing. The manual states:

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.

Motherboard manufactures test with many different vendors of Ram. (You can see the tested ram on page 2-12 of the P6X5D-E manual)

Most of the time, the motherboard can detect the proper latencies to configure the ram. One ASUS motherboard my company sold years ago, was not compatible with the Muskin ram we were selling at the time. Every new machine that was built, had to have the CAS latency manually set in the bios, otherwise every system would blue screen shortly after boot.

The manual further states the following pieces of information:

Installing DIMMs that are incompaible 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. (Page 2-24)

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.

So the answer to your question, the DRAM_LED is blinking because the motherboard is testing the ram. The leds blink faster the further through the test the motherboard is. There are no user interpretable blink codes


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You're right! I just checked the SATA power cables. Both ends are identical, but the cable arrangements are not. How can modular PSUs and their cable ends be standard, but the cable arrangements not? Argh! It would be on par with having different USB cable arrangements! –  l0b0 Jul 28 '13 at 5:45
About the patterns, I'm pretty sure those are the BIOS POST patterns, which are relatively well known. I'm looking for those relevant before POST, that is if the PC never reaches POST. –  l0b0 Jul 28 '13 at 5:47
A long continuous beep means that there is a problem with the power (not enough, or incorrect voltage/polarity). Other than that, there are no beep codes before the bios, which explains why you aren't finding any thing in google. –  spuder Jul 28 '13 at 7:09

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