What can we do at the moment to get this fixed?
Only Dell can answer your question. You can call their Technical Support line and post any findings to this thread on Dell's Community Forum until it is resolved.
Get Dell to replace the motherboard?
It's not clear (to me) where the fault lies:
- In the UEFI BIOS that could be fixed with an BIOS update
- In Windows 8, in which case it might be a Microsoft problem
- A fault on the motherboard seems unlikely because the four SATA ports work with Windows Vista and Windows 7 when the Legacy BIOS is enabled
How long does Dell's warranty last for?
- At www.dell.com you get "90 days Premium Phone Support + 1 Year In-Home Service after Remote Diagnosis" for an Inspiron 660. You can extend the support by paying extra for 1, 2 or 3 Year Enhanced Support.
- At www.dell.ca you get "1 Year Basic Service Plan" included for an Inspiron 660. You can pay extra for 2, 3 or 4 Year Basic or 1, 2 or 3 Year Enhanced Support.
You get what you pay for.