Didn't know what I was getting into until I started reading these Dell Forums. Purchased a XPS 12 9Q33 with i7 4510U CPU.
Intel released that i7 4510U CPU recently in Q2 2014. This suggests this laptop model line is still suffering from wake from sleep blank screen & image retention issues that a lot of others have reported from over 1 year ago.
Wake from sleep issues - XPS 12 9Q23
Wake from sleep issues - XPS 12 9Q33 Haswell CPU
7/2013 Dell A02 BIOS acknowledging wake from sleep issue with possible fix, but even the newest A06 BIOS doesn't fix the issue to this day 8/2014.
Screen Image Retention - XPS 12 9Q23, 9Q33
http://en.community.dell.com/support-forums/laptop/f/3518/t/19497269.aspx (66+ pg of complaints)
Dell should be ashamed for releasing such a terrible laptop with no fix. What is left of Dell if you screw over all your customers?
I just have the same wake from sleep problem with the newly bought XPS 12 9Q33! Tried the latest BIOS A06 and it didn't fix the problem at all.
Dell please fix this!!! I now regret trusting dell again after my old Studio XPS was broken like http://en.community.dell.com/support-forums/laptop/f/3519/t/19595547.aspx.