Five or six pumps? Wow. That's a bit more, in terms of both complexity and cost, than what I want to get into, if avoidable.
I'm looking at this in a couple of other ways, although not sure whether this is feasible.
First, maybe I can simply sacrifice chiller efficiency by running a pump that outputs flow at a rate lower than the labeled minimum for the chiller. The chiller's rating is presumably based on requirements for chilling large volumes of water (chilling tens of gallons of water in an aquarium system) rather than for the relatively small volume of water in a WC loop. Perhaps the smaller volume involved for a PC loop doesn't require the same degree of efficiency as cooling the water in a large tank. As long as going below the labeled minimum doesn't pose a threat of mechanical or electrical damage to the chiller, maybe it's not necessary to strictly adhere to the recommended flow rate range.
Second, I have indeed been looking at Martin's site, which is what prompted my questions asking for help choosing a pump in the first place:
In the bit-tech article
that got me thinking about using a chiller in the first place, a setup was described in which an MCP655 (fitted with an EK D5 X-Top) was used for its ability to reach the chiller's minimum flow rate of 5.3 gallons per minute (1200 liters per hour). Their loop included a Swiftech Apogee XT block on the CPU and an XSPC Razor block on the GPU (which is also a double-GPU card, as in my case). They got satisfactory cooling results, despite the fact that the restriction from their CPU block (and probably from their GPU block as well) at 5 gpm must have been pretty high
-- assuming they actually reached a flow rate anywhere near 5 gpm, of course. And they didn't aim for sub-ambient temps from their chiller.
I think the main differences between their setup and the one I am planning are that
- the chiller I will use has a higher recommended minimum flow rate (8 gpm vs 5 gpm)
- I am probably going to have 10-15 feet of additional tubing running to a second room while their chiller and pump were immediately adjacent to the waterblocks (but I would gladly eliminate this extra tubing if the chiller and the pump turn out to be quiet enough), and
- I would be willing to aim for sub-ambient temps.
setup worked despite the predicted restrictiveness of their loop relative to their pump's capacity at that high flow rate of 5 gpm, I'm wondering whether I could still get a system to work using an MCP655-type pump if I am willing to sacrifice a little of the chiller's efficiency by using a pump that doesn't meet the chiller's minimum flow rate.
(Sorry for the dissertation.