Hi everyone,
I’m facing a persistent "No POST" situation that is defying logic, even after replacing the motherboard and PSU. I’m looking for some deep-dive technical insights to break this deadlock.
1. The Backstory & Original Hardware
My system was perfectly stable until a few days ago. It started rebooting randomly without warning and eventually refused to power on at all.
Suspecting a motherboard failure, I decided to upgrade to an ASUS PRIME B550M-A WiFi II. After a meticulous assembly, the "No POST" condition persisted. Here is what I’ve observed:
Considering the failure was a "progressive" malfunction and that my previous PSU was 8 years old (and had been sitting idle for 2 years), I suspected the electrolytic capacitors might have reached their end-of-life. I replaced it with a Sharkoon Rebel P15 (650W, ATX 3.1, Cybenetics Gold). Result: Same behavior. No POST, solid Power LED.
4. Technical Analysis & Standoff
Coming from a professional background in laptop motherboard prototyping, I’m trying to visualize the Power-On Sequence. Usually, I would look for POST checkpoints via Port 80h, but I haven't found a detailed sequence map for this ASUS consumer board.
Thanks in advance for any technical insight!
I’m facing a persistent "No POST" situation that is defying logic, even after replacing the motherboard and PSU. I’m looking for some deep-dive technical insights to break this deadlock.
1. The Backstory & Original Hardware
My system was perfectly stable until a few days ago. It started rebooting randomly without warning and eventually refused to power on at all.
- Original MB: ASUS A320M-K
- CPU: AMD Ryzen 5 5500
- RAM: G.Skill Ripjaws V 16GB Kit (2x8GB) DDR4-3200
- GPU: GTX 1660 Super
- Storage: Crucial P310 500GB NVMe Gen4 + SATA HDD
Suspecting a motherboard failure, I decided to upgrade to an ASUS PRIME B550M-A WiFi II. After a meticulous assembly, the "No POST" condition persisted. Here is what I’ve observed:
- Beep Code Test: Without RAM installed, the motherboard buzzer emits the "No Memory" beep codes. This confirms the CPU is executing the initial BIOS instructions and the chipset is active.
- RAM Installed: Once both sticks (or even just one) are populated, the system remains silent. No beep codes, no video output (HDMI via GPU).
- Q-LED Core (Power LED): On this board, the Power LED acts as a diagnostic tool. In my case, it remains solid on. It doesn't trigger the blinking patterns for DRAM, VGA, or CPU errors.
- CMOS: Performed a full CMOS reset; no change.
Considering the failure was a "progressive" malfunction and that my previous PSU was 8 years old (and had been sitting idle for 2 years), I suspected the electrolytic capacitors might have reached their end-of-life. I replaced it with a Sharkoon Rebel P15 (650W, ATX 3.1, Cybenetics Gold). Result: Same behavior. No POST, solid Power LED.
4. Technical Analysis & Standoff
Coming from a professional background in laptop motherboard prototyping, I’m trying to visualize the Power-On Sequence. Usually, I would look for POST checkpoints via Port 80h, but I haven't found a detailed sequence map for this ASUS consumer board.
- The GPU Dilemma: If the GPU were the culprit, I would expect the Q-LED to signal a VGA error or the buzzer to emit 1 long and 3 short beeps. None of this happens.
- The CPU/RAM Paradox: The fact that it beeps only when RAM is missing suggests the CPU is alive, but the process hangs as soon as the memory controller is engaged or the handshake with the GPU begins.
- Has anyone experienced a "Silent Hang" where the Q-LED remains solid but the boot process freezes before reaching the VGA check?
- Is there any documented Power-On Sequence or specific checkpoint list for ASUS B550 boards that could explain why the diagnostic routine stops without reporting an error?
- Could a faulty GTX 1660 Super (perhaps a short on a secondary rail) be "clamping" the boot process so early that the BIOS can't even trigger a beep code?
Thanks in advance for any technical insight!