I have a Lian Li PC O11 case that cant take tall cooler like the Noctua NH 15, Be Quiet Dark Rock etc. so i need something low profile. I've had AIO water coolers before and hated them all because of the pump noise so i'd prefer to stick to air.
Thanks
Your PC 011 has 155mm CPU clearance so no reason to use flat cooler. Flat cooler with fan pushing toward motherboard dumps heated air in all directions. With fan pulling air away from mobo is better, but without case side vent directly over fan so still ends up dumping heated air everywhere. Good little tower will cool much better because it's flowing air front thru cooleer toward case's rear vent, so most of cooler's heated iar goes out the back of case.
Really need to know what RAM you have so we know cooler & fan will fit over it.
Standard Mugen 5 is £43.99
https://www.overclockers.co.uk/scythe-scmg-5100-mugen-5-rev.b-cpu-cooler-hs-046-sy.html
I would suggest Fuma 2 for £49.99 but it's out of stock.
https://www.overclockers.co.uk/scythe-scfm-2000-fuma-2-dual-fan-cpu-cooler-2x120-mm-hs-
Alpenfohm Matterhorn Black £46.99 is quite good. According to Alpenfohn website it is 156.6mm tall, but OcUK says158mm and your case spec is 155mm. I've squeezed 4-6mm taller than spec into many cases, so I'm pretty sure it will fit in your Lian Li. If you measure from surface of motherboard to where side cover fit to. I use a straight edge from top to bottom or front to back and measure to motherboard. If you have 164.6mm cooler will fit. Surface of mobo to top of CPU is 8mm or less.
https://www.overclockers.co.uk/alpenfohn-matterhorn-black-cpu-cooler-120mm-hs-050-al.ht
The 5c difference between plain and black Mugen 5 in room ranging from 21.5-23.4c means 5c could easily only be 3c .. and 3c is within margin of error in testing.
