That is the GPU support bracket. I removed mine because it was in the way when I installed my SB Z card in the bottom slot. This is the procedure to put it back in place: R10 service manual 
[IMAGE] Had a tech over today to replace the failing hard drive on my 3rd R10 since March, this one supposedly brand new.  The tech had no clue how to even open the case or access the interior.  When he left among other issues, he didn't close the case and this piece was just sitting inside the case for some reason.  So, is this piece important because I can't figure out how to put it back?
Aurora R10, is this piece important?