[NAME]    I measured and the fan definitely seems to be 120mm x 25mm.  Yes . . . definitely 120mm x 25mm . . . that is good news. The mobo has a 4-pin connector and the current OEM fan is 4-pin PWM, which means the speed of the fan can be controlled by the mobo. Personally, I prefer to use Noctua 3-pin fans, which cannot be controlled by the mobo and will spin at the top speed rpm constantly. The reason you can allow these fans to spin at constant top speed is because they are so quiet. The 3-pin fan connector will plug into the mobo 4-pin connector with no problem . . . like you said, there is a plastic guide making it idiot proof. This is the fan I used for all three of my case fans  Noctua NF-S12A FLX  The "top speed" is a quiet 1200 rpm, which worked well in my case. This is the Canadian version  Noctua  There are others that prefer the 4-pin fans, so review the Noctua web site for other options, and choose what you think will work best for you. You may want to go with a higher rpm fan, but keep in mind . . . more rpm means more sound. The decibels are published on the Noctua site.
Hi all, I have an XPS 8910 which has been working great since Jan 2017. I've noticed, lately, my top chassis fan is squeaking, so I'd like to replace it. I'm having a heck of a time finding online (or in the service manual) the specs for what kind of fan I should buy. Can anyone recommend a replacement fan that will be simple to install? (i.e. remove old fan, put new fan in its place, no messing with the bracket, etc). I'm in Canada, so amazon.ca is my best place to shop for this. Thanks! Chris
XPS 8910, need new chassis fan