I have one that seems to work fine. I have some issues getting it to auto negotiate the speed correctly on one of my switches but I've never looked into that much as it works on other switches. I'm not sure if its a switch issue or nic issue.
mskc0 at pci2 dev 0 function 0 "Marvell Yukon 88E8040" rev 0x13, Yukon-2 FE+ rev. A0 (0x0) I have one that works fine: mskc0 at pci1 dev 0 function 0 "Marvell Yukon 88E8053" rev 0x22, Yukon-2 EC rev. A3 (0x2): apic 1 int 16 But there are several variants of this chip, and some are buggier than others. Problems have been reported before. Unfortunately I have never been able to reproduce them.