Intel NUC D54250WYKH persistent BSOD

I have an Intel NUC D54250WYKH, which Ihave been trying to get running stably since May 2014. The symptom of the problem is persistent BSODs and freezes, which occur about 1 - 3 times per week. The configuration is:

Intel NUC D54250WYKH

8 GB RAM (2x Crucial CT51264BF160BJ)

Hitachi 1TB Travelstar 7K1000 SATA HDD

Plextor PX-128M5M 128GB M5M Series mSATA SSD

Windows 7 Home Premium 64bit

I have tried countless driver updates and hardware configurations (removing either stick of RAM, the SSD or the HDD) but none of these have solved the problem. There is no obvious pattern to the BSODs. Many different driver files are shown in the minidumps, but many of the BSODs point to ntoskrnl.

Looking for input from Intel as to whether there's anything else I can try, or whether I need to RMA the system.

Thanks.