I've had the fun of recently testing three low profile HSFs. I thought I'd summarize my findings here since low profile HSFs tend to be of interest to HTPC builders, especially those going SFF.The Contenders
Silverstone NT07-1156, $24.50 from Amazon.com, 37mm high
Titan DC-155A915Z/RPW, $19.98 from Newegg.com, 30mm high
Gelid Slim Silence i-Plus, $28.98 from Newegg.com, 28mm (1U) highThe Testbed
Intel G620 CPU
ASUS P8H61-I motherboard
Kingston 4GB DDR3 1333
Kingston 64GB SSD
Samsung 250GB 2.5" HDD
Iwill HT80 mini ITX HTPC caseThe Results
The Silverstone NT07-1156 is an oldie but goodie I've had around for a while. It's the tallest of the bunch at 37mm and it clips in like the stock Intel HSF. For both price and noise it comes in middle between the other two. It does a good job of cooling. There's not much to say here we don't already know.
Installs like the stock meaning you don't have to remove the motherboard
Quieter than stock
Decent price with good reputation
Installs like the stock meanng you have those plastic clips
The Titan was a new one I'd never heard of or tried before. It comes in a 30mm, 7mm lower than the Silverstone and only 2mm above the Gelid. It looks very much like a stock HSF, except it screws into a backplate on the motherboard. This requires removing the motherboard which isn't a big deal. Install was very easy. It did a fine job of cooling but was the noisiest of the bunch, to my ears about on par with the stock HSF. It was the cheapest of the bunch.
Allows more clearance than the NT07
Loudest of the bunch
The Gelid I'd also not tried before but it has a good reputation. At 28mm it's the shortest of the bunch at the "1U" height. It's also the most expensive. Unlike a lot of 1U coolers though it's not a server or blower style. It's hefty with a copper bottom and the paste pre-applied. Install was the trickiest of the bunch with tiny little black rings that had to be installed on each side of the mounting hole. There was a lot of flipping the motherboard back and forth to mount each clip which has three parts -- a standoff, a nut for the back and then a screw on spring with a nut for the top. It lives up to the 'Silence' in its name and does a great job of cooling. With that case I was using it became obvious that the 1U height is what it was designed for as I was able to mount the SSD under the ODD finally.
Short as it gets
Quietest of the bunch
Hardest to installConclusions
All these HSFs were good. They all cooled fine in a small case. IMHO, the Gelid was the best because it was the shortest and the quietest, at least for a 65W TDP CPU in a small case. It was the most expensive but only by $4.50. It was a bit of a chore to install but it's something you only need to do once or once in a while. If you've got headroom, the NT07-1156 is a good choice being the tallest. It's quiet and easy to install if you're used to the Intel stock HSF clips. It's also the most widely available it seems. I found it at several stores. The Titan is good and under $20 so a good choice for a budget build that needs a short cooler. It's the loudest of the bunch though. If you're sitting 10' away though it's not really audible.
As with everything, it depends on your budget and what you need it to do.