The PSU fan operates and illuminates during testing, yet it fails to function when connected to the motherboard.
The PSU fan operates and illuminates during testing, yet it fails to function when connected to the motherboard.
I hope someone can assist me… I’ve swapped in a gigabyte A520M H motherboard and a Corsair CX650 PSU for an A520M S2H and a CX750, but when I power on the system nothing appears. If I connect the PSU to a tester, all indicators light up. I’ve tried shorting the power switch with a screwdriver between the two pins, yet it still doesn’t work. In an experiment, I connected the old PSU to the tester and everything functioned normally, including the fan spinning. However, when I plugged the 24-pin connector into the old motherboard and turned it on, the fan didn’t spin. Using the new PSU with the old motherboard produced the same issue, so I’m unsure what connection might exist 🤷🏻♂️!
Your new MoBo, A520M S2H,
features VGA port available. It requires a -12V rail for operation.
Your previous MoBo, A520M H,
lacks VGA port.
Corsair has been reported to strip the -12V rail from their PSUs, as newer models no longer include VGA ports and Corsair assumed this change.
For clarity (as it can be confusing):
Old PSU linked to old MoBo – functional? Yes/No?
Old PSU linked to new MoBo – functional? Yes/No?
New PSU linked to old MoBo – functional? Yes/No?
Please note, you must also connect the CPU and RAM in the MoBo, along with the 24-pin ATX connector and an 8-pin EPS power cable.
Also, what CPU(s) are you referring to?
Thank you Aeacus, I wasn’t aware that RAM and CPU needed to be measured in MB. I plan to conduct further tests tomorrow. To better clarify the issue, the PC wouldn’t power on; after replacing the motherboard and PSU, it still didn’t start. Recording this has led me to suspect a possible faulty power switch!?
🤦♂️
MoBo alone isn't sufficient. It requires additional parts to function properly. MoBo acts as a bridge linking the CPU to other elements such as RAM, GPU, and SSD. If you only have a 24-pin ATX and an 8-pin EPS connected to MoBo (with the monitor attached, and if the CPU lacks an F-suffix), then connect the KB and mouse cables to MoBo's power and ground pins. This method skips the standard power button on the PC case. Check the MoBo manual, specifically page 16, section 9, to find the PW+ and PW- pins. Use a metal tip screwdriver to briefly connect them for power. To turn it off, flip the switch behind the PSU.
Finally, someone who seems to grasp my issue is reaching out again with useful advice, thank you 👍👍👍.
I don’t have time tonight, but I’ll check it out tomorrow and reply. I tried the shorting method before, but the new version is fixed in this case… I think I’ll need to take it out and test it from the desktop, though I’m still puzzled why something I’ve done many times didn’t work this time with such an unusual problem… Thanks a lot for your help so far. I’ll add more tomorrow (or maybe Monday).
It's best to test the MoBo on a breadboard. It's possible the MoBo might not work either. A DoA happens frequently with Intel A-series MoBos, as they tend to be the most affordable ones.