Power supply fan to motherboard


So I have an odd question. I had an old power supply that killed itself, a 1000w corsair something. It has a massive fan that I took out of it and wanted to use as a case fan. I did test with an old junker computer and the fan does spin when connected to a motherboard but I wanted your advice before I get it going with my main PC.

The fan is 12v .70A with a 2 pin connector, my motherboard only has 4 pin chassis fan connections, now I know that just hooking it up positive to negative will make it work, I'm wondering based of I guess the amps or connecting it in this fashion, could there be any long term damage to my motherboard.

Or on the flip side, would it be smarter to get a molex adapter or make my own adapter to power this fan. I've read that connecting the fans positive to the molex red will run it at 100% speed and I believe yellow will run it and a little under half. Is this true? Your thoughts and sorry for the long post.

The motherboard is an Asrock extreme 3 gen 3
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  1. There will be no damage to your motherboard.

    However, since it's a 2-pin fan it will run at 100% speed which is likely loud. Your Power Supply had a circuit that could VARY the voltage it sent the fan based on the temperature inside the PSU.

    Some motherboards are capable of this, but not most. I'm also not sure of the PIN connections of your 2-pin to the 3-pin on the motherboard. Does it even FIT on your motherboard?

    There are some case fans that run at 100% and are fairly quiet. It's common to have a combination of quiet case fans and others like the CPU that can VARY the speed (set in the BIOS and/or software).

    My advice is thus:
    a) use that fan as a case fan ONLY if it's quiet enough
    b) consider a quiet case fan instead
    c) optionally consider a 4-pin if the FAN connection you intend to use can control the fan speed (see your motherboard manual)
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