Sandy Bridge PCI Card Drivers Fail with "Disabling IRQ"
I wasn't aware of problems with PCI cards on Sandy Bridge (until I bought an Asus P8Z68-V LX) even though there seem to be quite a few reports out there. No fix appears to have been developed (I have tried 3.1-rc10). The only thing to help is booting with irqpoll kernel parameter which seems to reduce the number of occurrences.
The Sandy Bridge chipsets don't have PCI support anymore, that's why board vendors use a bridge chip. The ASM1083 is quite a common one but ASMedia doesn't seem to be very Linux-friendly. Usually PCI or PCI Express bridges just work, without needing a driver, but this chip is buggy and probably only tested with Windows.
I hope motherboard vendors will start to use JMicron chips instead. JMicron supports Linux somehow, as they list the minimal kernel version required for a device to work on their website.
That ITE chip is not the PCI bridge. It's the Super I/O chip which means it handles PS/2, parallel, serial, and floppy, and often also hardware monitoring, along with a lot of BIOS stuff. It's not related to PCI at all. You can't even see the Super I/O chip of a motherboard in the lspci output.
The first link clearly mentions it as a Super I/O chip.