Desktop CPU 12-Volt Power Path: No startup: check standby power upstream
Pattern to record: The PC has no normal start response before any CPU or graphics workload begins.
Identify the supply and load
The EPS/CPU connector feeds the motherboard’s processor regulators. Verify the cable against the PSU and board documentation; a PCIe graphics cable is not interchangeable just because a similar plug appears to fit. The dedicated GPU or EPS/CPU connector is not the ATX standby output; missing standby must be checked at the specified PSU-to-board connection.
Mains and connector safety
PCIe and CPU power plugs can look similar but are not interchangeable. Do not probe a GPU or EPS connector expecting an ATX standby signal.
Workshop checks
- Identify the PSU wiring and check its documented standby path before testing the EPS/CPU power feed.
- Once normal startup is restored, verify the EPS/CPU power feed connector and test its stability under a controlled workload.
Repair and loaded verification
If the checks support this cause, repair or replace the proven faulty supply or standby load; assess the dedicated power connector separately. Verification should cover cold POST, processor stress, sleep, restart and connector temperature.
For an assessment of your desktop motherboard, contact AEPC in Burswood or call 027 908 8880. Provide the model and the conditions that reproduce this problem. Workshop visits are by appointment.