PC won't boot / no display (no-POST)

The systematic no-POST checklist: from 'completely dead' to 'fans spin but no display', in the order that finds the fault fastest.

1. 1

   Define the symptom precisely

   Completely dead (no lights/fans)? Fans spin but no display? Powers on then off in a loop? Each points to different causes — note which one you have.

2. 2

   Completely dead: power path

   Check the PSU switch (I = on), try a different wall outlet (not a power strip), reseat the 24-pin and 8-pin EPS at both ends, and verify the front-panel power switch pins are on the right header pins. Still dead? Short the two power-switch pins with a screwdriver tip to bypass the case button.

3. 3

   Fans spin, no display: debug LEDs

   Most boards have four LEDs (CPU / DRAM / VGA / BOOT) — the one that stays lit names the failing stage. No LEDs? Listen for beep patterns with a case speaker.

   Tip: DRAM light is the most common: reseat RAM, try ONE stick in slot A2.

4. 4

   The classic fixes

   1) Monitor cable into the GPU, not the motherboard. 2) Reseat RAM (one stick, slot A2). 3) Reseat GPU and its power cables. 4) Reseat EPS 8-pin. These four solve the majority of first-build no-POSTs.

5. 5

   Clear CMOS

   Power off, unplug, and either move the CLR_CMOS jumper for 10 seconds, short the two CMOS pins, or pull the coin battery for a minute. This resets BIOS settings that may block boot (bad XMP, wrong display output).

   Careful: Unplug mains power before touching the CMOS battery or jumper.

6. 6

   Strip to minimum config

   Still nothing? Run outside the case on the motherboard box: board + CPU + cooler + one RAM stick + PSU only (use iGPU if available). If this POSTs, add parts back one at a time — the failure returns with the faulty part or a case short (misplaced standoff).

7. 7

   New CPU on an older board?

   A brand-new CPU generation on an older chipset may need a BIOS update to POST. Boards with BIOS Flashback can update from a USB drive with no CPU installed — check for a dedicated Flashback button on the rear I/O.