120mm foam fan gasket source?

[lifespeed]

Any silent PC experts in here have advice on how to quietly seal the gap between my AC Infinity aluminum fan mounting plates and my 6 Noctua NF-P12 redux-1700 PWM fans mounted with silicon "screws"? The silicon fasterners place a small vibration isolation disc about 1.2mm thick by 7mm diameter between the aluminum plate and the fan body. I did not install corner pads to the frames, as it would seem leaving the soft, small vibe-absorbing pads would be best. And it does appear to be quiet.

But it is a steep job to cool that close with hundreds of Watts dissipated. And the silicone mounts for the fans are giving me a 1mm leak between the fan and the aluminum plenum. I can feel some air movement with my finger tips near these gaps, I think. There are coarse green fiber filters both on the inlet and outlet inside the door. These are relatively free-flowing, but this is not a low-back-pressure application. There is some pressure behind the aluminm plenum.

I would like something soft to seal the gap, preferably very low durometer as I don't want to add stiffness to my silicone screw isolators. That's why I mention foam gaskets instead of all those silicone and rubber gaskets on the market. I think that is too much stiff material over a wide area, I just want to use the silicone screws. very little vibration is conducted into the aluminum plate this way, preventing it from acting as a triple-fan speaker board.

Any suggestions on a soft foam gasket?

Noctua fans https://noctua.at/en/nf-p12-redux-1700-pwm

[Olle P]

Why not just put some adhesive tape along the edges?
Half of the (tape) width on the aluminium plate and then angled up on the side of the fans. Even if it isn't a perfect seal it should provide enough flow resistance to basically eliminate the leakage.