The Genesis II Quiet Edition is a relatively new offering from Puget Systems. It packs the most workstation-oriented power possible into a quiet package, which is something we've built our reputation on. It supports two eight-core Intel Xeon E5 CPUs (115 W each), with expected support for the upcoming Ivy Bridge-EP family that Chris previewed in Intel's 12-Core Xeon With 30 MB Of L3: The New Mac Pro's CPU? It can take up to 256 GB of registered ECC memory, supports up to eight hard drives, and as many as seven PCIe 3.0 x16 devices (three are electrically wired x8 in 16-lane slots).
We experimented with dozens of cooling permutations in the process of finalizing this layout; heat sinks and fans pointing up, pointing down, pointing back, pointing at each other, and away from each other. We used our laser cutter to build custom ducting, heat chambers, and airflow baffles. The configuration you see to the right is the best of everything we tested. With such quiet fans, a big and open airflow design performs best.
You'll notice that only the rear-top fan is blocked off. The front is left open. This is by design, too. When is comes to working with high-heat, low-airflow systems, it's very useful to direct and channel air this way. The video card is down in the board's third slot, allowing ample room for the processor heat sinks to operate efficiently. Smaller add-in cards, such as audio or networking, can still be used in the top two slots.