Whats the 2-pass or 4-pass mean on a radiator?

[Mooker]

Hi. I'm thinkin about gettin the Black Ice Extreme. Wut does like 2 pass double row low pressure drop mean? And wuts 4 pass mean?

[cdrikari]

The # of passes is how many times the coolant passes through the length of the radiator.

So a 4 pass rad would typically go as such:


IN OUT
* *
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OCWC talks about the LPD mod and the pass thing here:
http://chipware.dynip.com/More_About_Mods.html