Adding pump question

[bolweval]

Was thinking of adding a second pump D5, to my loop to increase flow, right now my loop goes;

res-->pump-->rad-->rad-->cpu-->gpu-->gpu-->back to res. If I add the second pump after second res so the loop would be

res-->pump-->rad-->rad-->pump-->cpu-->gpu-->gpu-->back to res, would that be the best way to utilizes the second pump?

Any suggestions would be greatly appreciated, thx

Here's a pic of my rig in its current state.

[Jmark]

Nice looking build you have there! Looks very cool...

I think in the configuration you are running it's a good place to put the second pump. I have not tried it but would think the perfect spot for a second pump would be after the most restrictive block in your loop. That way you could pump up the pressure with the second pump after it has dropped off going through the restriction. It should increase the overall efficiency of the loop giving you more flow.
Have not tested this theory but may just try it out before I put my next build together.

John

[sswilson]

I get differing opinions on this but have yet to actually see a dual pump loop in action.

My concern with dual pumps in series is that unless they are perfectly matched for flow is that one part of the loop would have a tendancy to empty the other part of the loop.

[Jmark]

Originally Posted by sswilson

I get differing opinions on this but have yet to actually see a dual pump loop in action.

My concern with dual pumps in series is that unless they are perfectly matched for flow is that one part of the loop would have a tendancy to empty the other part of the loop.

You are bound to get conflicting opinions, as it quite difficult to actually calculate flows and pressures for such an arrangement.
The pumps do not have to be perfectly matched as each pump has its own inlet/outlet performance curve. If you stay within the curve you won't hurt the pumps and most of the pumps we use have a fairly large performance curve.
Personally I'm not sold on the idea of pumps in series as I just can't see where it is needed from a performance stand point. As a redundant pump yes, performance no.

[MpG]

Hmm, never noticed this post earlier for some reason...

Firstly, if you're looking for temperature miracles, I wouldn't get your hopes up. My own testing on the GTZ (with no other blocks in the loop) has been showing a grand total of about 1-1.5 degrees difference between one and three MCP355's running in series. With its higher heat dump, the MCP655 certainly isn't going to do any better.

Generally speaking, unless it's a serious mismatch between pumps, watercooling systems are fine as long as the loop is fully bled, as hydrostatic pressure keeps the pumps from starving each other.

A quick test you might want to try with your first pump: Do a temperature run, and see what temps you get. Turn the pump speed down one notch, and do it again. Turn it down another notch and repeat. If the temperatures aren't getting worse when slowing things down a little, the behaviour of flow/temperature curves make it almost a certain bet that temps won't get any better when speeding things up.

If you decide to go for a second pump anyway:

The position of the second pump is 99% irrelevant. The only thing to watch out for is when first bleeding a dual-pump loop - MCP655's can't be run dry, so only use the first pump until most of the air is bled out of the system. Also keep an eye on the reservoir, since running two pumps will lower the liquid level quite a bit, possibly below the plastic deflector shield. So if you top up the reservoir, and then turn the pumps off, all that water will try to return to (and overflow) the reservoir - make sure you fully tighten the cap first, and listen for a quiet hissing to warn you if the cap seal isn't perfect. Conversely, when the pumps are running, keep the cap open at least a little, as multiple pumps can actually give you vacuum/pressure problems that make it harder for the loop to bleed properly.

[JMCD]

^ Agreed, try lowering your current pump speed and see if anything changes. I don't think you're going to get too much of a difference.

[Dazmode]

Nice setup!

[biff]

I agree with a lot of what MpG says. People seem to get way to carried away with some WC equipment. Sure there will be benefits to bigger pumps and giant rads with screaming fans and solid silver water blocks (and to some that may be what they are after) but if you have a loop built with decent components to begin with then the added benefits of said equipment only drop the temps a degree or two and what does that really get you?

Since you have two rads and are considering a second pump why don't you split the loops and run a loop for the CPU that doesn't generate a whole lot of heat on it's own and is temperature sensitive, and then have a loop for the GPU's that do generate a lot of heat but are also a lot more tolerant of it.