BIOS-Update? I've not seen any Update for my X38 mainboard since 6 years. And all my PCs have the latest available BIOS and drivers.
Again to make it clear...:
Problem exists (in my case) with X38, P67 and Z87.
All have a SSD as the systemdrive and Raid5 for data. (Raid5 with 3 HDDs and also 4 HDDs)
Problem exist under Win8.1, NOT under Win7. (Win8.0 not tested)
Clean installation, just Intel chipset drivers and IRST (driver and software).
It has to be fixed... as soon as possible.