Running a 20 Pin ATX Power Supply to a 24 Pin Motherboard

A few days ago, one of my older desktop computers acted up on Windows. The symptoms were closely resembling a hard drive failure and upon reboot, the system ran a disk check supposedly fixing corrupt files but actually lead to a more severe system instability.

I started my past-due “backup before the hard drive dies” procedure and copied over my data files as necessary. Oddly, there were no hiccups during the copy process and the hard drive spinned up normally on both my other Macs and PCs.

A couple days later, I noticed an abnormal, slightly high pitched noise coming from the computer. It was hard to tell if the sound was coming from the power supply or the motherboard but upon detaching the power cables from the motherboard, I confirmed it was from the power supply I had, a Thermaltake TR2-430W.

Luckily, this power supply has a 5 year warranty but I wanted to confirm that this was truly the problem before RMAing the faulty part so I dug up one of my older power supplies and mounted it on to the case. While connecting the ATX power cable to the motherboard, I noticed 4 pins were short! Now, I knew a 24 pin power supply would fit on a 20 pin motherboard as the 4 pins would be extra, but the other way around was questionable.

This desktop was a rather old AMD Athlon 64 computer (nothing power hungry) so I just fired it up assuming it wouldn’t boot at the worst case. There was no problems at all during the boot up and my system was all back to normal. Upon further googling on the web, it seems the 20 pin connector works in a lot of cases except perhaps where the system is power demanding.

Of course, your overall system power consumption should never be higher than your power supply capacity so running a 20 pin power supply to a 24 pin should only be used when power levels are met and I believe my case was a perfect example of it.

Since it works well, I am planning to keep using my older power supply and will save the newer 24 pin as a backup or for a newer system.

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