The slk800/900 are too heavy to work well with the clip-on mounting method. You're going to want to use a mobo that has mounting holes.
According to reviews the SLK-900 provides only slightly better cooling than the SLK-800. If you're going to use the 900 on an Asus mobo, be sure to check the ThermalRight Web site to make sure that it will fit without having to bend some of the mobo capacitors over to make extra room for it.
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