Just my 2 cents. I have two Haswell boxes with Ubuntu Server 14.04 each running bunch of VMs. The first one is Intel Core i7-4770K and it runs only Linux VMs. There is no single MCE here for at least one year. The second box is Intel Core i7-4790K and it runs mix of Linux and Windows 2003 VMs. MCEs regularly appear in logs here.
Just my 2 cents. I have two Haswell boxes with Ubuntu Server 14.04 each running bunch of VMs. The first one is Intel Core i7-4770K and it runs only Linux VMs. There is no single MCE here for at least one year. The second box is Intel Core i7-4790K and it runs mix of Linux and Windows 2003 VMs. MCEs regularly appear in logs here.