Heat transfert from PSU

[MrPatate]

Hi,

This thread could have been in cooling, mod and in this section. Since my question is mainly about the PSU I chose this one, if I'm wrong, admins feel free to change the thread to another section of the forum.

I'd like to have your input on what I'm planning

My case is a Lian-Li PC-V2000 like this one (picture taken randomly on google):
Bottom mounted PSU and inverted motherboard.

I'm upgrading everything and want to change how the air flow goes in the case. The old setup is like in the picture. Since I'm really tired of all the dust, I'm covering all the holes at the bottom of the case (carpet, animal, lots of dust!). So the air wouldn't have a choice but to go from the front fan (filter), through the HDDs and at the back.

The new PSU has a 140mm fan blowing into the PSU and out at the back. The maker mention that the PSU is design to have the fan at the bottom (but could be installed fan on top if necessary) and the screw pattern only fits with fan down.

So here are my options:

1: Leave the new PSU like the old one was (fan at the bottom) with the 7/8" riser plate(remember the case won't have the bottom holes anymore). But I have doubts that the air from the front fan will simply go above the PSU and out. Maybe since the fan is so big, it will still be able to pull what it needs and keep it cool without an issue.

2: The case is very roomy, I could fit the PSU at the top (of the lower part) fan down, so the air from the front fan doesn't have a choice to pass infront of the PSU fan before exiting by the 2x80mm back hole. I would have to revert the back plate (2x80mm fan holes at the bottom and PSU slot on top), dremel a bit (the power switch is blocked by the inverted cutout), make holes to screw in the PSU and a stand to hold the PSU weight at the other end.

The 2nd option is more work, but also it raise a possible problem (which is why I came here instead of other sections of the forum):
How hot does the back(top) of the PSU will get? The back of the PSU will be against an aluminium plate and right above is the motherboard with the CPU (inverted motherboard, CPU at the bottom), the motherboard is flush against that plate(less than 2mm). So could the back of the PSU transfert a lot of heat to the CPU and motherboard and create more cooling problems instead of maybe solving a non issue for the PSU (if option 1 is actually a good one)?

Thank you!

 

[Tsumi]

The PSU fan will draw air into it. You don't need to worry about air bypassing it.

Properly made PSUs have fans operating on a thermistor or something similar. It will increase the fan speed as necessary to keep the PSU within its operating temperature. So again, you don't (or shouldn't) need to worry about overheating either.

 

[MrGreg62]

Why not install a filter on the bottom opening? Some filter material and some magnetic strips to hold it in place and make removal for cleaning easy.

 

[MrPatate]

The PSU fan will draw air into it. You don't need to worry about air bypassing it.

So basically option 1 should be fine. Just had doubts since there's less than an inch of breathing space.

For my personnal knowledge, if I did option 2, do you think a lot of the psu heat would have transfered to the CPU or PSUs don't generate that much heat?

 

[MrPatate]

Why not install a filter on the bottom opening? Some filter material and some magnetic strips to hold it in place and make removal for cleaning easy.

The case is aluminum, magnets wouldn't work. Even with filters the bottom would still suck very fine dust from the carpet.

 

[Tsumi]

So basically option 1 should be fine. Just had doubts since there's less than an inch of breathing space.

For my personnal knowledge, if I did option 2, do you think a lot of the psu heat would have transfered to the CPU or PSUs don't generate that much heat?

The Antec P180 I had had about 1 inch of space underneath the PSU. Never had any overheating issues, if it did I would have known by the fan ramping up.

How hot the PSU get is based on its efficiency and how much power you're drawing.

 

[rtangwai]

I have the Lian-Li PC201B which has the same layout as the PC-V2000.

Does your case have the wheels on it? Mine does not, just some small feet.

I put a couple of bricks at each end of the case so it is several inches off the ground.

Even on a carpet the extra height is sufficent to keep most of the dust out of the PSU - it is a fan, not a vacuum cleaner.

If you are really worried about the dust, instead of cutting your rear plate why don't you simply mount the PSU upside down when you rotate the plate? Unless your computer gets really hot it isn't going to pull in that much heat from the components, especially as the PSU is below the CPU.

 

[MrPatate]

I have the Lian-Li PC201B which has the same layout as the PC-V2000.

Does your case have the wheels on it? Mine does not, just some small feet.

I put a couple of bricks at each end of the case so it is several inches off the ground.

Even on a carpet the extra height is sufficent to keep most of the dust out of the PSU - it is a fan, not a vacuum cleaner.

If you are really worried about the dust, instead of cutting your rear plate why don't you simply mount the PSU upside down when you rotate the plate? Unless your computer gets really hot it isn't going to pull in that much heat from the components, especially as the PSU is below the CPU.

Yes I have the wheels, but the bottom vents are sealed (masking tape) anyway. I want to set it for positive pressure, so all those holes were a nightmare.

 

[Tsumi]

Positive pressure means more intake than exhaust. Vents without fans don't contribute to positive or negative pressure.

Edit: in fact, the point of positive pressure is so that excess air goes out all the cracks and vents in your case rather than going in due to negative pressure.