The G34 motherboards I've seen come with backplates, sometimes permanently attached to the bottom of the board. You would just put the heatsink's screws through the holes in the motherboard and into the backplate and then tighten.
As far as fans are concerned, the Dynatron A6 you linked there is probably the best one available here in the U.S. at the moment. The Thermaltake CL0017 also looks to be decent for a workstation, the rest are all noisy little side-blower units or passive 1U units for servers.
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