you can mount it anywhere you like but for most effective cooling have 2 case fans with one fan mounted at the bottom for intake (there's a fan slot just in front of the psu mounting zone) and one at the top of the case as an exhaust (this is in addition to the one at the back of the case).
the reason for this config is because we all know hot air rises. so you want all the hot air at the top of the cabinet gone and fresh air coming in from the bottom.
this should fix temps in your system.
ok, deepcool tesseract has:
1x120mm fan slot at the back
2x120mm on the side panel
2x120mm on the top and
1x120mm fan at the front.
what i suggest is put 2 fans as intake at the side
and if you wnat more then add 2 as exhausts at the top. that will fix your in-case temps.
Also, keep the psu's fan facing downwards for better thermals.
the psu position was designed so that excess heat from it doesn't enter the cabinet.
I received deepcool teserract today and I installed everything and cabinet came with one front intake and rear exhaust but the temperature of gpu remained same and when I contacted Zotac customer care regarding temperature then they replied that it is common thing and nothing to worry....is there something to worry about for idle temperature between 40-45 and 75 on load....pls reply