Today I decided to swap the motherboard in my CSI Linux machine. Since it was the exact same model as the old one, I figured it would be a straightforward drop-in replacement. Boy, was I wrong.
After carefully screwing the new board into the case, I powered it on… and it ran for about 5 seconds — fans spun up, lights came on — then it shut off completely. No POST, no BIOS screen, just a clean shutdown. I tried again. Same result.
This was especially frustrating because the system was running perfectly fine on the old board with all 4 RAM sticks and the original (admittedly old and cracked) thermal paste.
I spent the rest of the day troubleshooting:
- Dropped down to just 1 or 2 RAM sticks (including my known-good old stick)
- Removed the CPU cooler, thoroughly cleaned the old dried/cracked thermal paste, and reapplied fresh paste using the pea-sized dot method
- Double-checked the Intel stock cooler push-pins were locked correctly (arrows pointing outward)
- Reseated the 24-pin main power and CPU 8-pin power connectors
- Verified the CMOS jumper was in the normal position
- Confirmed the missing WiFi card had nothing to do with it
At this point, the leading suspects are either the cooler still not making perfect even contact with the CPU or a hidden short somewhere inside the case (extra standoff, bent I/O shield, pinched cable, etc.).
Tomorrow morning I’m doing the definitive “breadboard test”: taking the motherboard completely out of the case, removing the CMOS battery, installing only one RAM stick in the A2 slot, mounting the cooler with fresh paste, connecting just the 24-pin and 8-pin power, and shorting the Power SW pins with a screwdriver to turn it on.
This test should finally tell me whether the problem is a case-related short or something with the board itself.
I’ll update this post with the results once I run the test. If you’ve ever had a stubborn 5-second shutdown after a motherboard swap, drop your experiences in the comments!