I recently picked up an old system with fairly noisy fans. I'd like to replace them, but the fans themselves don't have any mention of their size. Now, I know that there's standard sizes like 40, 60, 80, 92, 120 (and non standard ones, like sticking a box fan on the side of your system).
My question is, how do I measure the size? Is it by the size of the blades, or the square casing they're in?
3 Answers
It's the length or width (doesn't matter because it's a square) of the frame in millimeters, not the blades.
You measure a computer fan along one edge, from the points where the screw holes are.
My question is, how do I measure the size? Is it by the size of the blades, or the square casing they're in?
What difference does it make? The frame is at most a few mm larger than the blades. For example, if the blades have a diameter of 76mm, then the fan is obviously an 80mm fan. Because for all intents and purposes, (ie, regular, consumer use) fans are standard sizes, so you can just round to the nearest size (there are no standard sizes that close together).
One time, I saw what I thought was a 40mm fan on a video-card which turned out to be in actuality 36mm:
Regardless, the fan itself had no frame, so with one, it would still have been a 40mm fan anyway.
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