Cooling 2x Thin Radiator vs 1x Thick Radiator

I'm trying to determine the best combination of radiators for use in a htpc -- space is limited; I have room for the following:

2x Thin radiators (Such as Alphacool Nexxxos Pro 120) with a single fan in between them, so they'd be operating in series.

1x Thick radiator (Such as a Thermochill PA120.1), again with a single fan.
A low noise fan would be used, and it would be on a fan controller.

Which would be most efficient?

Other components in the loop will include:
Swiftech Storm CPU Block
Swiftech MCW60 GPU Block
Alphacool 12v DDC Ultra Pump
XSPC 250mm Passive Reservoir (mounted externally)

Furthermore, there exists the possibility of adding a 2x80mm radiator externally on the exhaust fans. How much cooling do these provide? And is there any significant difference between Alphacool Nexxxos series radiators and the AquaComputer Evo series radiators, since these are the only two 2x80mm rads I could find?

The overall goal is noise reduction, since it's a HTPC, but it will house an Opteron 165, so some extra cooling ability to aid with overclocking is always appreciated.

Thanks for the help, and my appologies if this has been covered elsewhere - my search abilities may have failed me.

 

I'm no expert, but I would expect little improvement in temps from having 2 rads stacked together as you describe. (Interesting as it may be)
The 2nd rad would be getting warm air off the 1st, and the flow restriction wouldnt exactly help either..
- Would be interested in seeing results from such a config though.....

Seeing as that res will already dissipate *some* heat, I'm sure a single, decent 120mm rad will do you fine!
- Maybe try and find one of the new BlackIce GT's...?

- What GFX are you planning on btw?

 

To be honest I haven't yet decided on graphics, it will likely be an x1900 card so that I can add another and use crossfire when I need to upgrade later down the road. I've read about these cards being pretty hot though, so I may end up going for a x1600 series card instead.

 

A single rad will be more efficient than two (assuming equal size-i.e. one 120.2 vs. two 120.1's) simply because of the fewer number of 90deg. turns and barb transitions.

 

Moreover, sandwiching radiators is a bad idea. Each radiator is an airflow obstruction, and cuts CFM roughly in half. The first radiator suffers because the obstruction of the second radiator behind the fan causes a drop in its airflow (new air can't be sucked in without the old air being blown out, see?), and the second radiator suffers because it gets only half the CFM it normally would in the first place, with warmer air to boot.

 

the larger rad is a better way to go. i had two rads stacked an with 2 103 cfm fans there was next to no air movement. Nexxo is right, there is Way to much resistance for the fans to over come, and its louder than juat a single rad. Also why a storm and not a 1u apogee if space is an issue? i mean your not ocing this you just want it quite right?

 

Is it really worth it?

I understand that you want to OC your opteron a little but you can do that easily on one 120mm Rad. Nexxo has a dual opteron and ATI 98XX on running on a single 120mm Rad.

The whole purpose of a radiator is to slow the movement of water down, and then allow the fans to dissipate the heat. You will need to add fans to all of the radiators if you want to cool this effectively, of course resulting in increased noise. Running all of these radiators passively is not going to be worth it due to the drop in flow rates.

A triple radiator would be an option as they can be run passive and still stay well within spec. I had an Intel P4 running OC'd from 2.8-3.46 i a loop with GPU & Chipset. CPU idled at 32oC and 41oC under load. GPU maxed at 56oC. Of course fitting it may be an issue.

Good Luck

 

A single 120.1 BIX with a decent fan with shroud is more than capable to handdle what you want. Adding more rads will just hurt your systems and make things more complicated.