[Homebuilt] CPU fan spins once then stops. No post

nmathew

Distinguished
Dec 9, 2002
27
0
18,530
Hello.

I've assembled a new system, but I'm having trouble getting it to power on.

CPU: AMD A4-3400
MB: GIGABYTE GA-A75M-UD2H
PS: CORSAIR CX430 V2
RAM: Patriot Signature 8GB (2 x 4GB) PSD38G1600KH

This isn't my first build, but I'm running out of ideas. When I press the power button, the power LED flashes briefly and the CPU fan starts to spin up, then nothing. Pressing the power button again does nothing until I flip the hard switch on the back of the PS, wait a moment, then turn the switch back on.

I've verified that the power supply is properly connected (24 pin + 4 pin). I checked the CPU and heat sink seating. I tried one stick of RAM in various slots. I reset the motherboard and checked for unneeded risers which could cause a short. I disconnected all the front panel connectors and tried starting the system with just the PS button attached. I tried starting the system by shorting the front panel power button wires. I cleared the CMOS. I tried with a different power supply (old Ultra 550W modular). In that case, the CPU fan would weakly spin for a little bit, then stop, and the cycle would repeat. This is causing me to suspect there is a power issue somewhere.

After work I'm going to try removing the motherboard from the case and starting it either outside the case or in a new one. Sadly, the HTPC case I bought didn't come with a speaker, so I couldn't listen for potential error codes. I'll take one out of a system for testing after work. One concern I have is that Gigabyte's website states that the A4-3400 is supported since BIOS F2, but that the A4-3300 is supported since F4, which is fairly recent. The two chips were released on the same date, and I'm wondering if Gigabyte has a mistake on the website and I need to flash the board. Being a new platform, I don't know anyone with another FM1 board or CPU.
 

rolando

Distinguished
Jan 16, 2012
1
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18,510

same problem for me, the cup fan would only spin once, hdd is good, power suppply is also good cause i tested it on another pc, its either the cpu or the board, ill buy a new board
 

tienle355

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Apr 9, 2014
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4,510
there was a 4 pin Power connector on the motherboard that needed to be connected from my power supply in addition to the main power connector to the motherboard. Until my experienced friend broke off the 4 pin connector from the 6-pin original setup from the power supply and I connected this 4-pin connector to the motherboard, voila! Everything worked as expected. Wish there was an important note on the MSI H81M-E33 V2 instructions that states must supply power to the 4-pin JPWR2 connector in order for system to work. Oh well, learned a lot this problem. Costed me a bunch of time ...