I have an old tower I am going to build my first unraid system in, but the 5 1/2" bay's have little "shelves" bent inwards that you can use to slide optical drives into.  If i understand it right, these would be in the way of all the HDD stackers out there?  Has anyone tried to bend them back to get it out of the way so the sides are flush? 

 

I'll try to get a photo of them if that description is unclear.

MAny of the bays have those support tabs.

I've had to bend a few in my day.

The kingwin 3in2 trayless removable have slots to allow the tabs to slide through.

Some of the others also have that. Most do not.

It all depends on the model.

So for those that you do not, bend them very carefully.

 

 

So for those that you do not, bend them very carefully.

 

 

So...I shouldn't mention my method of using a screwdriver and a hammer?

 

You should be able to tell in the pictures whether the stacker has little slots or not.  Many are made for that company's cases, or a specific line of cases, which do not have that problem (i.e. the CoolerMaster Stacker case and their 4-in-3 offering).  It can be a pain to bend the tabs in without damaging the case, luckily I'm not too worried about how the case looks internally so I just beat the tabs in until it's good enough.

Note that the slots in the Kingwin units are pretty shallow... the tabs on my Thermaltake Armor case were about 3/16" and just barely made it