On the Q08 you can fit a Thermalright AXP-140
and a 140 fan with a normal ATX PSU, check Mini ITX H67 Silent Gaming System
, also check in the thread that with his components the AXP140 doesnt block the PCIe slot, you would need to check your mobo to see if the clearance is the same. Now the Q11 seems slightly narrower, but the AXP-140 has 70mm height, so it should fit fine, the problem might be the fan, if you are not doing anything demanding, try passively, with just the frontal case fan pushing and the PSU fan pulling from it... you will have to test it, but there is also low profile fans, like Scythe Kaze-Jyuni Slim Slip Stream 120mm x 12mm Fan - 1200 RPM (SY1212SL12L)
so that should be 70 + 12 = 82 mm that should clear your 88mm.