Hello everyone,

I received my new LF iii 420 in the mail yesterday and was super excited to put it in my system. First of all, the AiO feels much better than the old one thanks to the softer tubes and the pump design. The AMD mounting mechanism on the other side is not as easy as the rev. 7 mounting with the old liquid freezer. It might be easier to install the AiO in a new system, but installing it in my case with the other hardware in it was kind if tricky. It took me a while to figure out the best way to mount it, here are my tips:

1. Make sure you have enough tube length left so there isn’t too much tension from the tubes that moves the pump block

2. Align the screw holes and tighten the screws alternately so that there is the same tension on both sides. I had the problem to tighten the left side more than the right and then the right screw jumped out of the hole. (The GN video really shows this issue)

3. If you align the screws and can’t get the screw to thread into the mounting hardware, wiggle it a bit until you hear the screw sliding into the hole.

4. community tip: mount the pump to the bracket first and then mount the whole thing to the motherboard (or loosen motherboard screws while mounting pump)

I might undo everything and mount the pump again because I’m not sure how good the thermal paste is spread after my installation. For now I don’t have any thermal issues and the AiO edges out its predecessor by a bit.

I hope this text will help someone, I’m pretty sure arctic support will give different advice but it worked for me.

Edit: I did return my LF3 because of the mounting mechanism. Had to change cases and the mounting got worse for me. Really disappointed in Arctic.

Edit 2: I didn't think this post would get that much traction. I hope someone at Arctic reads this and works on a better solution.

Please pin this on top to save a lot of unnecessary questions.
Tips to edit this are welcomed.

This superb cooler comes with two options - one cable to power them all or a separate cable for each thing.
Use all in one cable plugged in CPU_FAN header if you don't care about noise, possible tiny performance loss, or don't have enough fan headers available.

Majority of modern motherboards support all of the provided cables on all headers.
To be sure it's safe you can find a maximum load for each header in your motherboard's manual and power requirements of each part on Arctic's website.

• Pump: 0.35 A

• VRM fan: 0.05 A

• 120 mm fans: 0,1 A (0,11 A for ARGB models) x2 for 240 and x3 for 360 models

• 140 mm fans: 0.12 A (0,17 A for ARGB models) x2 for 280 and x3 for 420 models

Best practice is to set all the headers to PWM mode in bios. With DC there is no way to control the fans.

• Daisy chain the 2 or 3 fans you have on a radiator and plug FAN cable to a CPU_fan header.

• Pump cable goes to a PUMP_fan or whichever header says "PUMP" (if there is no such header then use CPU_OPT or simply a SYS_fan).

• Finally a VRM cable goes to a CPU_OPT or a SYS_fan.

After plugging it all you can either use BIOS or motherboard's software to control the fans. Best thing to do is to use a FanControl software with much more settings. For that there are other guides.

https://getfancontrol.com/

Just install a black lf3 360 rev.2 it was a pain the second screw Just did not want to go in so i try many times with huge force on the second screw i have install four lf3 rev.2 very easy but this one was a pain so maybe the spring thing is difference from unit to unit