PSU orientation help

[Billman]

I'm hoping for some help deciding which way to mount my PSU. I think a lot of my confusion is around just not understanding if the fan on this PSU is an intake fan or an exhaust fan. So knowing that alone would be a big help.

Here's my build:
https://pcpartpicker.com/user/pshopper/saved/#view=cjTmgs

Case: Silvestone GD05 (sort of an oversize HTPC, horizontally oriented)
https://silverstonetek.com/product.php?pid=241&area=en

PSU: PRIME Ultra Titanium 650 W 80+
https://seasonic.com/prime-ultra-titanium
(select 650 model, #SSR-650TR )

SeasonicPSU installation instructions:



How to position your power supply

seasonic.com




When sitting normally (writing right side up), PSU has a fan on top and is vented out the back. All other sides are boxed in.

It's my assumption that the PSU fan blows OUTWARD like an exhaust. If this is not the case please let me know as it totally changes my conclusion about what to do.

For flat desktop style cases, Seasonic recommends facing the fan towards the mainboard. Not an option with this case. Must be facing up or facing down in corner of case.

Also, first preference is to face PSU fan upward, but ONLY when there is 5 cm of clearance above, AND/OR the case has a ventilation panel on TOP. Well, it's about 4.3 cm of space from the top of installed PSU to top of metal case wall. Also, there are vents, but they are not "top" vents. They are corner vents just above the PSU. Each corner vent is maybe 1.5 cm x 9 cm. There are two. So neither criteria is met, but each criteria is MOSTLY met. There is a nice sized vent on the bottom of the case just below where the PSU mounts.

My feeling is even though I don't 100% meet either criteria, it's pretty close on both counts, and I should use this method and mount it rightside up with PSU fan on top.

Yes/no?

Image tells the story:

Not only that, but this case is inside a cubbyhole inside a wall unit with air holes galore above and below. Whole idea is that heat will escape by going out the top of the case or out the back (aided by two extra 80mm rear case exhaust fans). Again, I'm assuming the PSU fan blows OUT rather than sucks in. Idea for this case and location in the cubby is that heat goes out the back and then up, or in case of PSU, goes straight up.

The other option is to mount the PSU with fan facing down. There is a nice sized vent on the bottom of the case. However, fan blowing out would blow heat DOWN out the bottom of the case. This seems wrong because it's possible heat may well get sucked back into the intake fans.

SECOND QUESTION:

Okay, while I'm here.. it's been a while since I did a build and it's my first micro-ATX. Mobo is Micro-ATX. PSU is ATX / Intel ATX 12v form factor.

Mobo: ASRock - B450M PRO4 Micro ATX AM4
http://asrock.pc.cdn.bitgravity.com/Manual/H170M-ITXac.pdf

In terms of main power to mobo, on the mainboard itself, there are two interfaces located on adjacent edges of the mobo. (2x5) ATX12v1 AND the (2x12) ATXPWR1. I think I ONLY need the (2x12) ATXPWR1, right? I just leave the ATX12v1 unused, right?

Back at the PSU:

I'm using the modular cable and connecting to BOTH interfaces (2x5 and 2x9) in the M/B slot section (bottom right of image), right? Then this goes out ONLY to the mobo ATXPWR1 (2x12)? Right?

Sorry I know this question has been asked here before, and I actually did RTFM on this where I thought it pertained, but am still confused. Seasonic's manual is skimpy and useless in this regard. (BTW, Seasonic really needs to relax a bit on the over- the-top gratuitous packaging. This is a PSU, not the lastest iphone)

Build is on pause until I make sure I'm not blowing it up with the PSU.

 

[UsandThem]

I generally mount my PSU with the fan facing up in the case. I also disable any "fan stop" feature so the fan runs at low RPMs all the time. This is optional doing it this way. However, almost all PSU manufacturers recommend to always disable the "fan stop" feature if a person mounts the PSU with the fan facing downward (as the heat rises and sits in the PSU housing).

And to answer your other question, the fan blows downward on the components inside the PSU, and the heat is forced out of the back grill area (the area where you plug your power cord in).

 

[Campy]

The PSU pulls air in on the large flat side(top) where you can see the fan, and pushes it out the smaller back side. It looks like your case has venting under where the PSU sits, so you could mount the PSU there in an upside-down configuration, and it will then pull air in through the venting underneath and push it out the back, without having any impact on the airflow through the rest of your system. If you choose this configuration, make sure the hybrid fan mode is disabled so that the fan always spins.

 

[Billman]

The PSU pulls air in on the large flat side(top) where you can see the fan, and pushes it out the smaller back side. It looks like your case has venting under where the PSU sits, so you could mount the PSU there in an upside-down configuration, and it will then pull air in through the venting underneath and push it out the back, without having any impact on the airflow through the rest of your system. If you choose this configuration, make sure the hybrid fan mode is disabled so that the fan always spins.

Yep, you got it right. I contacted Seasonic to be sure and they said it was an intake fan. I finished the build an hour ago, installing just as you describe.

I do have the hybrid mode turned off as it's intended to be used with an up facing fan. However, the fan doesn't always spin because on this model the fan doesn't start until 40% load.

Thanks for the help! I'm not sure how "best answer" works but if I was I'd give it to you.

 

[UsandThem]

I do have the hybrid mode turned off as it's intended to be used with an up facing fan. However, the fan doesn't always spin because on this model the fan doesn't start until 40% load.

If you disable the "fan stop" feature by using the button, it should spin all of the time regardless of load.

When the "fan stop" feature is set to on, it won't turn on the fan until it hits a certain load or temperature.

 

[Iron Woode]

it sits with the mesh side down. Your own pic of the PSU shows the orientation as the Seasonic name is written upside down on the side in your pic.

The mesh side sits on this part of the case:

https://silverstonetek.com/product.php?pid=241&area=en#lg=1&slide=7

Personally, I prefer the Thermaltake Core V1 Extreme case for my HTPC.