Using PSU fan for cooling in SFF: is less efficient better?

[janas19]

I am looking to build a SFF system using the new Sugo SG13. I'll be using a non-K, air-cooled i5-2500 and a 140mm ATX PSU. The maximum height allowed for the cooler is 61mm. I plan on using the stock cooler, so I'd like to have hot air around the CPU exhausted out for better case temps.

My question is would an 80+ Bronze PSU actually be better than a Gold one, so that the 120mm fan spins more, thus venting more air from the case? Oddly enough, it seems like having a more efficient PSU with a lower spinning fan would be less helpful in this setup. Am I picturing this right or do I have it wrong?

 

[Black5Lion]

No, I think the fan spinning depends on the temprature.
So a higher effeciency is better because it produces less heat in the PSU, thus having more headroom for the heat coming from your cpu.

 

[janas19]

No, I think the fan spinning depends on the temprature.
So a higher effeciency is better because it produces less heat in the PSU, thus having more headroom for the heat coming from your cpu.

That makes sense. Any more info on the best PSU to use in terms of venting? Would any 120mm Gold PSU be fine, or is there a better criteria for picking? Seems like a "smart" PSU that senses the temperature of the air would be pretty good.

 

[Black5Lion]

That makes sense. Any more info on the best PSU to use in terms of venting? Would any 120mm Gold PSU be fine, or is there a better criteria for picking? Seems like a "smart" PSU that senses the temperature of the air would be pretty good.

I'm really not sure about this, but I think PSUs with bigger fans are better for this kind of thing. The added size of the PSU itself should help it handle the heat pretty well.
Also IIRC running a PSU at a lower wattage than it's rated usually lands lower temps, so get something slightly overkill.

 

[janas19]

I'm really not sure about this, but I think PSUs with bigger fans are better for this kind of thing. The added size of the PSU itself should help it handle the heat pretty well.
Also IIRC running a PSU at a lower wattage than it's rated usually lands lower temps, so get something slightly overkill.

Thanks, but I'm a bit worried. Here's why. Say for example I get a 500W Gold PSU. I'm running an Ivy i3-3220 and a GTX 750. So I have about 55W of CPU and 75W of GPU, thus ~140W power consumption. Now if the PSU only has 140W going through it, then do you think it might get hot enough to run the fan high and exhaust the case?

Sorry if I'm being a pest, I'm trying to understand it

 

[Aibohphobia]

If that's the hardware you're putting in there then why not just put a 120mm in front? The positive pressure from that one fan will be more than enough to keep the case cool.

I've done a single 140mm intake and no other case fans with a 5930K and GTX 780 and it was just fine.

 

[Black5Lion]

Thanks, but I'm a bit worried. Here's why. Say for example I get a 500W Gold PSU. I'm running an Ivy i3-3220 and a GTX 750. So I have about 55W of CPU and 75W of GPU, thus ~140W power consumption. Now if the PSU only has 140W going through it, then do you think it might get hot enough to run the fan high and exhaust the case?

Sorry if I'm being a pest, I'm trying to understand it

If the hot air get's inside the PSU it will raise the temperature and the fan will run faster the way I understand it.

If that's the hardware you're putting in there then why not just put a 120mm in front? The positive pressure from that one fan will be more than enough to keep the case cool.

I've done a single 140mm intake and no other case fans with a 5930K and GTX 780 and it was just fine.

Oh and this.
I have a C2Q+650 in a different case (atx, but small tower like the ones you find in schools) and the only fans I have are the ones on the CPU/GPU/PSU (one in each). No mesh for intake in the front or anything either, my 450w bronze (acting as exhaust) keeps things cool enough.

 

[janas19]

OK, that's reassuring. Probably one good 120 or 140mm fan should do the trick. Thanks!