Flow, is there a general rule

[dustin1706]

No real need for a second pump in that setup. Unless that ram block is extremely restrictive you should have pretty good flow.The effect of flowrate on temperature is not a linear function and once you are past a certain point (which is dependent on your hardware, but seems to be ~1gpm) there is very little gain to be had. There is some room for improvement as more turbulent flow is more efficient at heat transfer etc. , but it's not that much. IE: I run variable speed D5s and my max temp is only 2* lower on setting 5 than on setting 1 (prime95 + furmark 1 hour).

[concinnity]

Originally Posted by dandelioneater

I think the only point to using a second pump is for redundancy in the situation that the first pump dies. Just make sure that you plumb in your loop methodically and use the least amount of tubing as possible.

I agree. Unless you are running a massive loop, dual pumps are excessive. If you are worried about the pump failing, a system will shut down when temps get too high. Your system will be down, but not broken. Might be good to have a spare pump on hand though. To put it in perspective, ( lowfat's Big Lian Li ) is a pretty big loop, and he only uses one pump.

[Dazmode]

In my tests temps start climbing really badly if you go below 1L/m.