I'm not familiar with the XTM 510, but I had the same issue with an IBM Proventia MX1004. Really nice, tidy and unobtrusive little thing with 4 gig ports and serial console. But fire it up and REEEEEEEEEEEEEEEEE ... (at exactly the right pitch to bore through human skulls)
I opened it up and found the fans were connected using standard 3-pin connectors like you find on PC motherboards, so I fitted some resistors like this and now it's barely audible, while temperatures are barely unchanged.
Hopefully you'll be able to find a neater solution but this may be an idea if not. Just keep an eye on your temperatures, and be careful around the power supply.
her ya go op just plug this in between fan and motherboard.