80mm radiator. What can it cool?

[JonJ678]

I know the answer is 'not much' but I'm not hoping for much. I'd like to screw it onto the back of my psu, which uses an 80mm fan. Reviews seem non-existent.

The hope would be for sub 70 degree light load temperatures on an 8800gt (not a problem) and an i7 running as severely undervolted as I can get it to boot at. The benefit would be to have a system with only one fan running for office work and films, which I think is as quiet as I could get the system without using a fanless psu. I'm sure there's some people here from the time before 120mm radiators were the norm

I have the 54mm thick 20 fpi black ice one in mind, probably with 90 degree fittings on it. Nice and restrictive I know, but needs must.

Amazed that I can't find a single review of this. I've emailed hwlabs asking for a graph of delta t against heat dissipation for a range of static pressure fans, may as well ask for the ideal. I wonder if they'll even get back to me. I'm estimating 200W load, but don't know to be honest.

If a single 120mm radiator holds a delta t of 15 degrees (say), and the 80mm radiator has about half the surface area, is it a fair guess that it'll hold a delta t of 30 degrees for the same load? I don't think it's looking very likely that this idea is going to work, I'll be blowing hot air from the psu over the fins for one thing. For another if I ever have the air hotter than the radiator (likely) it's going to make the rest of my loop hotter.

 

[Monkey Puzzle]

I know the answer is 'not much' but I'm not hoping for much. I'd like to screw it onto the back of my psu, which uses an 80mm fan. Reviews seem non-existent.

Surely it's going to do even worse when taking in hot air from the psu?

The hope would be for sub 70 degree light load temperatures on an 8800gt (not a problem) and an i7 running as severely undervolted as I can get it to boot at. The benefit would be to have a system with only one fan running for office work and films, which I think is as quiet as I could get the system without using a fanless psu. I'm sure there's some people here from the time before 120mm radiators were the norm

I have the 54mm thick 20 fpi black ice one in mind, probably with 90 degree fittings on it. Nice and restrictive I know, but needs must.

I'd be worried about the psu fan being able to deal with getting airflow from all the psu components and pushing through a densely-finned radiator as well - the psu fan is probably temperature-controlled (most are from what I can tell) rather than load-controlled, but it may run at high rpm as a result, or worse, not be able to spin fast enough to cool the psu okay.

Amazed that I can't find a single review of this. I've emailed hwlabs asking for a graph of delta t against heat dissipation for a range of static pressure fans, may as well ask for the ideal. I wonder if they'll even get back to me. I'm estimating 200W load, but don't know to be honest.

If a single 120mm radiator holds a delta t of 15 degrees (say), and the 80mm radiator has about half the surface area, is it a fair guess that it'll hold a delta t of 30 degrees for the same load?

Would depend upon the airflow- assuming 80mm radiator has about half surface area (64/144) and about half the airflow of a 120mm fan then yours seems a reasonable assumption.

I don't think it's looking very likely that this idea is going to work, I'll be blowing hot air from the psu over the fins for one thing. For another if I ever have the air hotter than the radiator (likely) it's going to make the rest of my loop hotter.

Yeah - you could always put an accelero s2 on the 8800gt passively - supposed to work okay, and the cooler is only about £15 iirc. Though if it's only the psu fan running (and pushing through a restrictive radiator as well) might not work as well as in cases with better airflow where it's worked before...

 

[JonJ678]

Cheers man. I hadn't put any thought into the psu's health itself, thanks for pointing out this fairly severe omission.

860W pc power and cooling. 85% efficient at 800W is 120W to dissipate internally at full load. Taking draw when underclocked to be 200W at 80%, that's 40W to dissipate. So about a third what the psu can handle in terms of heat to get rid of. I don't think the 80mm delta is going to care so much about the radiator being in the way as to be unable to cope. I'm certain its thermally controlled too, so I think while underclocked the psu will be ok.

When overclocked, it might draw 500W at 85%, I think this is an overestimate for my computer. 75W to remove is still a lot less than 120W, and if the fan's running at full speed the noise won't matter so much relative to the case fans. I think you're right, this is going to be hard on the psu. I reckon the pc p&c will cope, but I'm glad to have checked a few of the numbers.


Noise is tricky. The psu fan spins faster, but then there's a radiator in the way so it should be more difficult to hear. Any idea how I judge whether the increase in noise from psu fan speed will exceed the decrease in noise from running the rest of the case fanless? I'm guessing there's not a hope of working it out and I'll have to buy one and see

Passive would be a disaster with zero airflow sadly, I've got a thermalright cooler for it in a box but it doesn't cope at all well under load unless there's a lot of air moving over it. Plus I'm fond of the 125mhz overclock on the gpu core

Thanks again, appreciate your post. I'm aware that this is not a normal place to put a radiator so it's a bit hard to find information on it

 

[MikeTimbers]

Could you put it on the intake of the PSU?

 

[JonJ678]

Probably not. There's very little space there, the psu and a 240 radiator are both mounted in the top of the case and it's only just long enough. It would get cold air through the radiator but hot air through the psu, I'm not sure that's better than the other way around for psu health. It also removes the muffling benefit of having the radiator between the fan and me