RonnieG,
how bout a shot at dd cooling???
I've done direct-die before.... well actually direct-slug - there weren't exposed dice before, until when I removed the K6 cap... DD didn't do well then, even with the low-power K6 (just 30 watts I think), and won't do well now with our 100W+ progressively smaller dice... Well maybe it'd work if you had a high-pressure/volume pump (think pressure washers) then you'd have to worry about eroding the die...
...
So, I've transformed it parallel (valve-less):
...slapped on some steel plate "magnetic shielding" and a coat of spray paint.
It's done.
Conclusions:
1) Pumps in serial add up the head
2) Pumps in parallel develop lousy pressure. With both pumps on it could only do 13 inches, contrast with the 26" of the serial setup.
3) When 1 pump dies or is turned off in a valve-less parallel setup, some water will inevitably short-circuit through the other pump BUT water will still circulate through the system and save it from catastrophe. With my low-drag components my temp increased only ~1*C when one pump is turned off.
4) Some pumps have startup problems when in serial (e.g. Resun SP-600). It seems that an existing flow through the pump, like what would happen in a serial setup when the other pump starts first, prevents the pump from deciding which direction to turn. This seems to happen when the pump is of a fixed-impeller design (ie the impeller is rigidly fixed to the rest of the rotor). Some pumps have worked around this problem by allowing the impeller some degree of movement independent of the rotor, so that the rotor can start spinning freely WITHOUT the burden of the drag caused by the impeller blades. So when attempting a serial pump mod choose pumps that are NOT fixed-impeller.
So if you see a pump mod on the internet that tries to reduce noise by fixing the impeller to the rotor. Don't. The impeller is "free" for a reason...
5) "Redundant" doesn't imply "unused"
Serial or parallel pumps ARE redundant. When one pumps stops spinning due to a stuck rotor, faulty electronics, etc, the system lives.
6) If you take care not to put in sewer primodial soup into your system you will NEVER have to worry about clogging your pump (unless you do something else stupid). As such you really don't need to protect against such incident.
7) If you put in distilled water you will NEVER have calcium buildup in your pumps.
8) If you have an all-copper system you will NOT have to worry about galvanic corrosion clogging up your pump...
9) Someone needs to take a vacation...
Cheers. Be safe
