What each LED means
At start-up, the motherboard queries the processor, checks the memory, polls the graphics card, then looks for a boot drive. If a check fails, it stops and lights the matching LED.
- CPU: the processor is not detected or does not work.
- DRAM: the memory (RAM) is not detected or does not work.
- VGA: the graphics card, or the processor’s video output, is not detected or does not work.
- BOOT: no boot drive is found, or it does not respond.
What matters is the LED that stays lit. ASUS speaks of an LED that is “always ON” after power-on; MSI’s manual of an LED that stays lit until the problem is solved. On Gigabyte boards, a lit BOOT LED means the operating system has not been reached yet.
The part named is not always the faulty part: for a DRAM LED that will not go out, ASUS also has you reinstall or swap the processor as a last resort.
The colours by brand
The LEDs’ names, places and colours change with the brand and the model. The reference is the label printed next to the LED and your motherboard’s manual.
| Brand | Maker’s name | Colours given | Good to know |
|---|---|---|---|
| ASUS | Q-LED | CPU red, DRAM yellow, VGA white, BOOT yellow-green (tech specs of the TUF GAMING B650-PLUS WIFI) | Some boards have a single light, the power LED, which blinks at a different rhythm for each part (Q-LED Core). |
| MSI | EZ Debug LED | No colour in the manual read (B450-A PRO MAX): read the label | The LED stays lit until the problem is solved. |
| Gigabyte | Status LEDs | No colour in the manual read (B650 AORUS ELITE AX ICE) | BOOT lit: the operating system has not been reached yet. |
| ASRock | Post Status Checker (PSC) | Red (B650M Pro RS manual) | The DRAM LED may blink during memory training: that is normal. |
A “yellow LED”, a “white LED” or a “green LED” therefore means DRAM, VGA and BOOT on an ASUS board like this one, not necessarily on another brand.
The safe checks
These checks need no tools and no part removed. Before touching the inside of the PC, switch it off and unplug the mains cable: MSI asks for this before installing or removing a component.
- Note which LED stays lit, whether it blinks, and take a photo. If your board has a two-character display, note the code too.
- Check the power: wall socket, power strip, switch at the back of the power supply. On the motherboard, the 24-pin connector and the processor connector or connectors must be plugged in: ASUS advises plugging in all three when the board has three.
- Check the screen: if there is a graphics card, plug the cable into it and not into the motherboard’s output, and select the screen input that matches the cable (HDMI or DisplayPort).
- Unplug USB sticks and drives and other devices; keep the screen.
- If you changed a BIOS setting (XMP, EXPO, overclocking) just before the fault, clear the CMOS to go back to the original settings, with the PC switched off and unplugged, following your board’s manual (button or jumper depending on the model).
- If the processor is new, look up in your board’s CPU support list which BIOS version it needs. If your BIOS is older, it needs an update: if you have never done one, leave it to us.
- Switch on again and see whether another LED lights up: it shows where the start-up stops now.
By LED: what next
CPU LED (red on ASUS)
Start with the processor’s power cables (step 2) and, if the processor is new, with the BIOS version (step 6). The next steps ASUS gives mean taking the processor out: reinstalling it, a clean socket, bent or broken pins. Our advice: if you have never removed a processor, stop before this step and bring us the PC.
DRAM LED (yellow on ASUS)
During memory training, ASRock states that it is normal for the DRAM LED to blink. Our advice: right after a build or a change of memory modules, give the PC a few minutes before concluding there is a fault.
If it stays lit, ASUS has you check, in this order: modules fully inserted, clean contacts, memory from the board’s compatibility list (QVL), the slots the manual recommends, then a start with a single module, adding the others one by one. A failed manual overclock is also among the causes ASUS gives for this light: clearing the CMOS (step 5) brings back the original settings.
Which slots to use, XMP and EXPO, and memory that is not detected are covered in our RAM guide.
VGA LED (white on ASUS)
With a graphics card, check that its power cables are plugged in properly and that the screen is connected to it. ASUS then has you reinstall the card, check the PCI Express contacts, then try another card.
Without a graphics card, the processor handles the display: it needs built-in graphics, and ASUS points out that not all of them have it.
BOOT LED (yellow-green on ASUS)
The board finds nothing to start from. Our advice: if the BIOS screen appears, check whether your SSD or drive is listed there.
ASUS has you reconnect the SATA cable at both ends, refit the M.2 SSD with its screw tight, check the contacts, then try another cable, another port or another drive. A drive that is detected can also leave this LED lit: ASUS lists problems of the operating system among the causes.
Without the four LEDs: blinking, Q-Code or beeps
A single blinking light (ASUS Q-LED Core)
Some ASUS boards do not have the four LEDs: the power LED blinks instead. According to ASUS: fast blinking (0.25 s cycle) for the memory on an Intel board or the processor on an AMD board, slow (2 s) for the display, very slow (8 s) for the boot drive, steady light for a normal start.
A two-character code (Q-Code)
High-end ASUS boards have a small display that shows a two-character code when an error occurs at start-up. ASUS explains that this code gives the most probable cause, that the codes differ slightly from one board to another and that you should read the table in your board’s manual. So we do not copy any table here.
After a successful start, the display on recent boards shows the processor temperature: a number shown once Windows is running can therefore be a temperature, not an error.
Beeps
If a small speaker (buzzer) is connected to the board, ASUS gives these signals:
- one short beep: the start is normal, check the screen and its cable;
- no beep: processor or memory not installed properly;
- one long and two short: memory problem;
- one long and three short: graphics card problem, and the power supply must deliver enough power if the card needs a power cable;
- one long and four short: processor fan, temperature or voltage.
These signals are those of ASUS’s FAQ. For another brand, follow your board’s manual.
When to stop and bring us the PC
- Smell of burning, smoke, sparks: unplug the PC and do not switch it on again.
- The LED stays lit after the safe checks.
- The next step means removing the processor or trying another power supply, other memory or another graphics card.
- A BIOS update is needed and you have never done one.
- You see a bent pin, a damaged connector or a burn mark.
In the workshop, PC4GAMER looks for the cause before proposing a part, and the solution is explained to you before any repair. The diagnosis levels, as the diagnosis page lists them:
| Level | Price | For |
|---|---|---|
| Remote help | CHF 30 | Windows still starts |
| Workshop diagnosis | CHF 60 | Crash, heat, noise or unstable FPS |
| In-depth analysis | CHF 120 | Intermittent or complex fault |
The exact price is confirmed after reading your request.
Frequently asked questions
What does the yellow LED on the motherboard mean?
On ASUS boards with Q-LED, the tech specs say: CPU red, DRAM yellow, VGA white and BOOT yellow-green. A yellow LED there means the memory. Other brands may use other colours: read the label next to the LED.
The VGA LED (white on ASUS) stays lit: is the graphics card dead?
Not necessarily. First check its power cables, the screen cable and the input selected on the screen. ASUS then has you reinstall the card and check the PCI Express contacts before trying another card.
The DRAM LED blinks right after the build: should I switch off?
Not straight away. ASRock states that it is normal for the DRAM LED to blink during memory training. Our advice: give the first start a few minutes before concluding there is a fault.
The BOOT LED stays lit but the BIOS appears: is it serious?
Not necessarily. On Gigabyte boards, a lit BOOT LED means the operating system has not been reached yet. Our advice: check in the BIOS whether the Windows drive is listed.
Should I buy a part when an LED stays lit?
No, not before the checks. The LED shows where the start-up stops, not always the faulty part: for the DRAM LED, ASUS also has you check the processor. The diagnosis avoids buying the wrong part.
My motherboard has no such LEDs: how can I tell?
Some ASUS boards blink the power LED at a different rhythm for each part (Q-LED Core). Others have a two-character display or a speaker that beeps. Your board’s manual says what it offers.
Sources
Pages read on 8 November 2026. Colours, codes and menus change with the brand, the model and the version: your motherboard’s manual and your parts’ documentation are the reference.
- ASUS : [Motherboard] ASUS motherboard troubleshooting via Q-LED indicators (updated 07/04/2026)
- ASUS : [Motherboard] Troubleshooting - No Power/No Boot/No Display (updated 05/03/2026)
- ASUS : [Motherboard] FAQ of Q-LED Core (updated 11/06/2026)
- ASUS : [Motherboard] How to use buzzer to troubleshoot monitor display issues (updated 14/08/2024)
- ASUS : TUF GAMING B650-PLUS WIFI, Tech Specs (no date shown)
- ASUS (Edge Up) : PC won't boot? Q-LED and Q-CODE turn your biggest PC building fear into a simple fix (4 May 2026, updated 1 September 2026)
- MSI : B450-A PRO MAX, manuel (E7B86v4.0) (no date shown)
- Gigabyte : B650 AORUS ELITE AX ICE, User's Manual (revision 1102, © 2024)
- ASRock : B650M Pro RS / B650M Pro RS WiFi, User Manual (version 1.0, March 2023)