The heatsink and fan combination I am using on my 5200+ is another Thermalright product, the SI-128SE, along with an adjustable speed 120mm fan that pushes a maximum of about 93cfm. The SI-128SE is a blow-down style heatsink, which is great for cooling the memory since the fins overhang the DIMM slots. However the mosfets are a bit farther away from the socket and do not fall under the CPU cooler's wingspan, so the HR-09 only receives a small amount of indirect cooling from the fan. Using a tower-type of heatsink would most likely put the upper section of the mosfet cooler in the path of airflow, assuming the fan was facing towards the rear of the case.
Since the HR-09 is really a passive style of cooler, in order to achieve a bit better performance I've also rigged up this duct or directional vane you might call it. It's just a simple piece of poster board angled underneath the fins of the SI-128 to direct some of the air out to the side facing the HR-09. The other half of the heatsink remains unaltered in order to continue to blow air down over the DIMMs.
As you can see, the HR-09 does provide a small amount of benefit at the default processor settings, 3-4° C at both idle and load. However the low voltage requirements of the CPU at this speed really don't cause the mosfets to heat up much. Now let's see what happens when we up the juice.
The difference in temperatures now is a bit more dramatic. The HR-09 keeps the mosfets 5° C cooler at load when used passively, and up to 9° C with a small amount of air directed at it. It's kind of a shame there's no means of attaching a fan to the HR-09. A small 40mm chipset fan would probably do nicely, but even with the blow-by from the CPU fan alone the results are very respectable.
I always knew overclocking put an additional strain on power components, I just wasn't aware how much. Oh I've made sure to size my power supply appropriately for the system, and provide ample cooling for the processor, memory and chipset, but up until now I'd not given the motherboard voltage supply much thought. Shortly after getting this board I happened to feel the areas around the CPU socket and was alarmed to find the mosfets hot to the touch. Being as this is one of their "overclocking" TForce boards, it's surprising Biostar chose not to use any type of stock mosfet cooler at all. Certainly there were provisions for one.
But as usual, Thermalright comes to the rescue with another great cooling product, the HR-09. With three different sizes and two different types, chances are you'll find one to fit your particular motherboard. And if you're doing any sort of overclocking you're probably going to need it. I would definitely take into consideration how to direct some air at it, as performance is greatly improved when being actively cooled. But even in a passive state the HR-09 is better than nothing at all.
The quality of this cooler is very good, as we have come to expect from Thermalright. Their proprietary through-hole design is a carry-over from their line of High-Riser CPU coolers and the single 6mm heatpipe works very efficiently, carrying the heat to the upper section where it can be more easily cooled. The mounting clips are really a no-brainer, the only scratch-your-head moment that I had was trying to figure out which side of the thermal pad went against the base, and after removing both backing strips it became sort of obvious.
You may have to do a little digging, but I was able to find the HR-09 available online for right around $20. There just don't seem to be many places that carry them. That's about the same price as Thermalright's chipset cooling solution, the HR-05, and the two are designed to work well together. If you happen to have a motherboard with two banks of mosfets, well then between the three you're looking at $60 worth of heatsinks just to keep the board components cool, which may seem a bit excessive considering you've still got the major components like CPU, memory and video card to think about. But if you're running a highly overclocked system and the thought of all that expensive hardware going into thermal meltdown has you feeling just a bit concerned, the Thermalright HR-09 mosfet cooler is right up your alley.