Although the fans are working are they working correctly? You may be able to see them spinning but just how effective are they. You could have dodgy ram (even the best sometimes get faulty batches). When the computer freezes at start up does it restart if you leave it for 10 minutes or so or does it simply refuse to start? If the system is failing the system restore will probably not work. In my opinion it should have been called windows restore. Although you can "rollback" to older or previous drivers it hardly restores the hardware (system). What yo could try is to run for a while with just the original ram and see if the problem recurs ( once sorted again). You could also run a memory test but be warned it takes several hours to complete a full test.