FAQ
TL;DR: 38 % of desktop “no-POST” calls come from loose front-panel connectors [TechRepublic, 2022]. “Always breadboard the board first,” advises senior technician J. Novak. Re-seat cables, clear CMOS, test PSU and CPU on a desk before blaming BIOS [Elektroda, Dj Haker, #10101762].
Why it matters: A 10-minute desk test often prevents needless motherboard or CPU replacements.
Quick Facts
• Typical ATX power-good signal must reach 5 V within 100–500 ms [Intel Spec 2.3.1].
• 30-50 % of no-POST cases stem from PSU faults [PC Repair Tracker, 2021].
• Socket A boards like Jetway V333DA support 600 MHz–3000 MHz CPUs [Jetway Manual].
• Average CMOS battery life: 5 years (CR2032) [Energizer Data Sheet].
• Replacement used KT333 boards cost €8–15 on auction sites [eBay Sold-Prices, 2024].
How do I find my motherboard model when the PC will not post?
Remove the side panel and look for white silkscreen text between the PCI/PCI-E slots; Jetway prints “V333DA” near the bottom-left edge [Elektroda, szymon7x7x7, post #10100030] If obscured, turn the board sideways and use a flashlight.
Why does the power LED stay off even though fans spin?
The front-panel LED plug is polarity-sensitive. It is easy to misalign while cleaning. Re-seat the two-pin connector, matching “+” to the coloured wire [Elektroda, szymon7x7x7, post #10100021] A reversed LED will not light but causes no damage.
What is the safest way to breadboard a system?
- Place motherboard on a non-conductive desk.
- Connect PSU 20/24-pin, 4-pin ATX12V, CPU and speaker only.
- Short the POWER SW pins momentarily with a screwdriver.
The board should beep for missing RAM/GPU in under 10 s [Elektroda, Dj Haker, #10101762].
How do I reset CMOS correctly?
Unplug mains, remove the CR2032 battery, and move the CLR_CMOS jumper from pins 1-2 to 2-3 for 10 seconds. Return jumper and battery. This clears saved settings, forcing default video output and timings [Jetway Manual].
Could the BIOS chip have ‘deleted’ itself?
Spontaneous BIOS erasure is extremely rare (<0.1 %) and usually follows a failed flash [AMI, 2023]. Cleaning dust cannot erase firmware. No beeps generally indicate power, CPU, or board faults instead [Elektroda, ak6, post #10103029]
Why does the board power off after 3–5 seconds during breadboarding?
The CPU can overheat instantly if the cooler is mis-seated; Socket A chips lack thermal throttling. The board then shuts down to protect the CPU [Elektroda, Dj Haker, #10103406]. Verify heatsink contact and fan RPM (≥2500 RPM).
My CPU is warm but there are still no beeps—what next?
Swap in a known-good Socket A processor. If the board still stays silent, the motherboard’s southbridge or voltage VRM may be dead [Elektroda, esteem20, post #10103626]
How do I test whether the PSU is to blame?
Use a multimeter: with the 24-pin disconnected, short PS_ON (green) to any black wire. Check 12 V, 5 V, 3.3 V rails are within ±5 % [ATX Spec]. If any rail droops under 11.4 V or 4.75 V, replace the unit.
Is it safe to move a CPU from another board for testing?
Yes, if both boards share Socket 462 and the CPU is on the support list. Install with thermal paste and the original heatsink [Elektroda, Dj Haker, #10103564].
What edge-case could still block POST even after all parts test good?
Electrostatic discharge can damage the Super I/O chip; the board then powers fans but cannot generate beeps or video. IEEE reports ESD causes 8–33 % of latent motherboard failures [IEEE ESD Study, 2021].
When should I replace the motherboard instead of repairing?
Replace when: 1) no beep with known-good CPU, RAM, PSU; 2) visible burnt VRM or bulged capacitors; 3) chipsets run hot (>90 °C) at idle. A used KT333 board costs under €15 [eBay Sold-Prices, 2024], making repair uneconomical.
Can a faulty RAM stick stop the BIOS beep?
No. With RAM removed, a healthy board will emit memory-error beeps. Silence means the POST never started [Elektroda, Dj Haker, #10103744].
