It seems that Gigabyte never considered a dual-CPU system when they designed the plumbing for the 3D Mercury case. It was only when I started installing the second CPU block that I noticed that the feed nipples on the distribution blocks aren't all the same size. The company apparently only envisioned the two auxiliary spigots feeding less needy components such as the chipset and graphics card via tubes of lesser circumference. Can't say as I blame them. It's been a long time since the last multi-CPU craze.
Looking at the photo below, the CPU feed is on the left, the middle feed shows the smaller nipple, and the third feed is the smaller size capped, giving it the appearance of being the same size as the first at first glance... (the large tube hanging free is from the second CPU cooler block)
Notice the flow control valves on the two secondary feeds.
The upshot is that I'm either going to have to run the CPU blocks in series off of one pipe, which has the advantage on cutting down on tubing but means cooling two CPUs with one feed, or find another distribution block with two of the larger size nipples. Running both CPUs off of one line might not keep the CPUs cool enough. I could opt for another cooling solution, but that would really cut down on the kewl factor, and you know it's all about the kewl.
There is an interesting closed system liquid cooler from Asetek (seen below) that I might consider but we'll have to see. I have an email in to Gigabyte about another distro unit. I'll definitely be trying the serial approach before I do anything, though I'll be paying close attention to the hardware monitor in the BIOS when I first hook it up. Currently, the QX9775s are running about 29 to 31 degrees centigrade under low load conditions with the Zalman coolers doing their thing.
Cheers, Jon
Addendum: After a comment from a reader, I realize the best approach would be to use splitters. Running in series would mean already heated coolant for the second CPU so it would run substantially hotter--not a good thing. I'll pick up two, one pre-, one post.






