I think you could
put a different heatsink in there, but I don't think it would mount all that well considering it's an Atom Ion combination. If you could get the heat sink to position properly, it probably would fit without the Blu-ray drive.
If you are just taking fans, I am already running a 120mm X 25mm fan facing down on the heatsink and it fits perfectly.
Just to put your cooling fears at ease, the 120mm fan on the stock Zotac heatsink works really well and the CPU temps are all within the spec limits according to Zotac engineers. They said the CPU should run between 60Â°C-90Â°C under load, 30Â°C-60Â°C idle. My unit runs maximum 65Â°C under load.
How much headroom do you have in there if you want to put in a bigger top down cooler or a mini-tower cooler?
I wanted to ask the same question!
Would if fit something like an Scythe Ninja if you didn't have the DVD-ROM drive?