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Rad size for 400w+ of heat?

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Albuquerque

Member
Joined
Mar 26, 2003
Location
North America
Ok, so here's the deal:

My PSU seemed to be the limiting scenario in my overclock; I've rigged a pair of them to my case to temporarily get around the problem until my TTGI 550W gets here in a day or three. My 3.0C is now able to hit 3.9ghz stable at 1.63v actual. By most of the online and offline calculators, I figure this processor is throwing around 110-115w of heat at this speed and voltage. Combine that with my upcoming X800XTPE which will (somehow or another) hit at least 560 core, and I expect to have my WC setup munching approximately 180w of heat.

Here's my thought process:

I want to pick up a MeanWell S-320-24, and strap a 172W/24v pelt to my CPU along with an 80W/24v pelt to my GPU. This will effectively dump another 250w+ of heat into my watercooling system.

Thus, I'm going to end up with over 400w of heat to get rid of in my WC setup. The question is, what kind of radiator and fan power am I going to need to dump all of this to the outside world? I've got one of WA2's dual rads (9.5" long, 5 1/4" wide, 2" tall, all copper) with a pair of 120mm x 35mm Delta's pulling and a BIG 120mm x 55mm pushing (oddball shrowd setup).

Is this going to be enough, or do I need to get a little crazy?
 
OP
Albuquerque

Albuquerque

Member
Joined
Mar 26, 2003
Location
North America
It's also too big for my mid-tower case. If I need more radiator surface area, I will likely opt for something that is essentially similar to a BlackIce Extreme with stacked 120mm's, or something like a pair of Swiftech 80mm mini rads or something.

Essentially, I'm out of room up top, I'm out of room at the bottom, and I'm out of room at the front. The room I have left would be the back section that's "above" the I/O panel near where the processor HSF would normally sit. I have plenty of room right there to mount something such as the rads I described above. My case has mounting holes for either twin 80mm fans or a single 120mm fan. Thus, I almost automatically have room for mounting equivalent rads.

The actual question still stands though: do I really need more radiator surface, or is a dual-sized core going to work? It's almost identical to the favorite '77 Bonneville all-copper rad -- it fits slightly more than two 120mm fans.
 

nikhsub1

Unoriginal Macho Moderator
Joined
Oct 12, 2001
Location
Los Angeles
The rad you have should be fine... although, a 172W pelt on the CPU ain't gonna cut it... you need a 226W pelt for that. Not even sure an 80W will be OK for the vid card, but I dont know how many watts it puts out.
 

felinusz

Senior Overclocking Magus
Joined
Feb 26, 2003
Location
Taiwan
First off, you will have trouble finding a 50mm (the size your typical peltier-ready CPU waterblock fits) 172W/~24V peltier, as they only come in a 40mm size (as GPU blocks typially fit), as far as I know. In any case, a 172W peltier will also probably be inadequate for getting your processor down to the temperatures you probably want to see from a peltiered setup, and which you can get with a solid 226W/~15V peltier.

40mm, 80W peltiers (the ones commonly shipped with Actively cooled GPU waterblock kits) peak at ~16V, not 24V, and only handle at around ~55W on 12V, as off of a computer's PSU. Here's a link to Danger Den's Peltier section (just for reference, you can get them cheaper elsewhere) CLICK HERE

An 80W peltier on your X800 XT won't get you below ambient after you start overclocking, and tossing volt mods into the mix. If you are certain about pelting your water circuit, you would probably be better off with a 172W/~24V peltier for your GPU, and a 226W+ peltier for your processor. Alternatively, if you wanted to stick to just one dedicated PSU, you could just use a 172W/~24V peltier on your video card, and run it down at ~15V with your CPU peltier. Running peltiers near their VMax will lead to diminishing returns; the extra heat produced often outweighs the diminishing gains more voltage gives you, and ends up giving you worse results.


All that aside, you will need some hefty radiatorage to handle the heat output of all this. However, you also need to keep in mind that your Peltier's hotside has a bit of leeway when it comes to temperature, your Peltier's hotside can be very hot, while the coldside can still be very cold (even below freezing).

I have a Chevette heatercore in a water circuit with a 172W/~24V peltier being run on 22V, on a heavily overclocked and overvolted 9800 Pro, and the heatercore is being strained, almost past it's capacity, by the heat load produced by the card. The air coming out of the Heatercore is hot, while the air going in is room temperature cool. Although the peltier hotside and waterblock are both quite warm, the GPU itself idles near freezing point.

With that in mind, I would say that a pair of Chevette Heatercores in parallel would serve you well. A Caprice with two to four 38mm thick fans on it would probably do the job as well. I would avoid smaller radiators like the DTEK Junior, BIX, BIX2, etc. which are better suited for single block, low heat-load systems. Those 80mm BIM radiators would be thoroughly inadequate for your system, even without peltiers. The radiator you have now should pretty much cut it, given that it's shrouded, and that you have some thick, high-pressure fans on it.

Sorry for the long post, I hope it's helpful though.
 
Last edited:
OP
Albuquerque

Albuquerque

Member
Joined
Mar 26, 2003
Location
North America
I think you guys overestimate what I'm looking for... I don't want my CPU or my GPU to be freezing or anything close; I'm aiming for high teens to low twenties in celcius. A 172W TEC (barring size constraints, I'll look into that) should give me a true DeltaT of about 20c if I'm doing my math right. That would bring my CPU to somewhere between 20 and 25c...

The 80W TEC may indeed prove to be too small and may necessitate a bump to 172W -- but that's a LARGE bump. I don't want to freeze the damned thing, I just want it in the 20's or so.

I understand the theory and the math behind TEC's and how you mate them to your heat-producing devices; I've done all of that. I'm just trying to see if a pair of TEC's will overpower my poor little rad.

From the sound of it, they just might... WHich means I may look into adding a second (or more) rads in parallel to my existing unit.
 

felinusz

Senior Overclocking Magus
Joined
Feb 26, 2003
Location
Taiwan
Look at it this way; you can always undervolt your peltiers to keep your coldside temperatures higher (and minimize the heat load on your water circuit), and then raise the voltage later on if/when you decide you wouldn't mind going a little bit colder.

A 172W/~24V Peltier has a wide range of options - run on 15V with your 226W CPU peltier it won't be as much of a heat concern for your circuit, but will still do a superb job of cooling your GPU. Or you could run it on 12V, signifigantly lowering the heat, but probably still keeping your card near ambient at load, unless you're overvolting it a lot. Later on, if you decide to, you can use a dedicated 24V PSU to hike up the voltage a bit, and get your card cooler.

Using an 80W peltier on your graphics card is, in my opinion, simply limiting your future options. A 172W/~24V pelt on 12V is nearly the equivelent to an 80W/~16V pelt on 12V (172W/~24V peltier on 12V = ~66W, 80W/~16V peltier on 12V = ~55W), and will dump a comparable amount of heat.