What is "head"?
 

...No, I don't mean what Monica did to Bill... :D

I don't have a water cooling setup yet, and have have had one, so I'm doing some research to find out what the best components are. One spec I've noticed is this "feet of head", and I have no idea what it actually means. The only thing I can think of in a watercooling setup that might be measured in feet is total length of hosing, but then why wouldn't it be called "feet of hose" instead of "feet of head"...anyway, what is it, and how does it relate to determining the capabilities of a pump? Is more head good or bad? (Once again, remember I'm talking about pump specs... ;))

Oh, and as long as I'm doing research...I know there are tons of "what's best in this situation" questions and answers, here and on plenty of other websites, and that's what I'm researching, but I figure as long as I'm asking this question...if you want to toss in your comments, by all means, feel free...

System will most likely be built into a CoolerMaster CMSTACKER case. I want the system to look "stock" from the outside; in other words, no radiators sticking out the back or Koolance systems on top, etc. Quietness is a goal, although I'm not going for silence. I'm thinking of mounting two radiators inside the case, one to the 80mm blowhole and one to the 120mm back outlet. (So, here I need advice on what radiators to use and what fans.) I want to put waterblocks on the typical components (CPU, GPU, and chipset), but haven't yet determined how to configure the loop (comments welcome). I'd prefer to use just one pump to keep things simple (make and model of pump?). I understand a reservoir should usually be the last thing before the pump, correct? Finally, what should I use for fluid...I mean, besides the water, of course. What additives should I...umm...add? One thing I know I want to try is something that will make the water glow under UV light. (I only said it had to look stock from the outside, remember!)

Head is basically the resistance of the flow in the loop.

EDIT: In other words the more restrictive the loop is the higher head rated pump you want. 300GPH at 0 head means there is no restriction in the loop. 300GPH at 3 feet of head means there is enough restriction in the loop to equal putting 3 feet of vertical pipe/tubing on the outlet of the pump and then measuring the flow at the end of the 3 feet of tubing/pipe.

haven't heard that one before. I guess swiftech is trying to protect the integrity of their lead hitman

So more is better...OK.

What, then, is "maximum" head--does that mean that's the most resistance that can be present with the pump still working at all; in other words, more resistance and the pump just stops? For example, the Swiftech MCP650 has a "Maximum head" rating of 10 feet. Now this pump also has a "Maximum discharge" rating of 317gph, is it assumed that this is with 0 head if the flow rating doesn't otherwise mention @ how much head?

Yeah, the pump will be unable to push water after the max head pressure is reached. Yes, generally if no head is specified then the number given is at 0 head. That number is useless though. You really need at least one other number to show the true power of the pump. One 317GPH pump might max out at 5ft of head while another may max out at 13ft of head. More GPH does not equal higher head max (very common misconception).

I'm going to assume that three waterblocks and two radiators is a relatively restrictive design, correct?

I'd appreciate it if you could point me in the direction of some comparisons between some of the top pumps available now. I've just started reading the ProCooling Pump Comparison here by pHaestus, but that article is almost a year old and I'm sure there have been some newer, better pumps out since then. Or just let me know which pumps to consider seriously.

Pumps have been around for quite some time now..... way longer than us geeks sticking them into PC's anyway..... I don't think there is much to improve on, when looking at pumps....

My take on head, it's how high up a pump can push water vertically into the air.

flow resistance appears to the pump as an artificial form of head, but there is a theoretical difference..... a pump with 12feet of head, say, will not move a single drop over 12 feet. In this case the pump is fighting against a directional force, Gravity..... if the pump stops, the water will come rushing down again....

That same pump with a 3/8" loop that's say 50Yards in length and flat on the ground...(representing a flow resistance of , for argument sake 15 feet's head, will still manage to move a slight amount of water through it.... in this case the pump is fighting against friction.... which it not a force by itself, I.E when the pump stops the water wont suddenly come flowing back the opposite direction....

almost like trying to get to 0 by dividing 358749 by 2, over and over and over..... you will never get to 0....