On Sat, 29 Jul 2017 19:26:36 -0700 (PDT), Tim R
wrote:

I run the headphone jack of the PC we use for internet into a Yamaha AV amplifier and a set of stereo speakers. It's not an audiophile system but it's much better than PC speakers.

It would be really convenient to stand the amp vertically to save desk space. But it has vents top and bottom, none on the front back or sides.

Can you run these vertically? or do they need the airflow from the bottom to stay cool enough?

If you consider how it cools itself normally, it probably draws a
small amount of air in though the bottom and passes it out the top,
plus random air movement of air from the top of the board out though
the top grille.

So, depending on where the vents were (all along or just specific
locations) you might find it could be made to cool better when on it's
edge because you could get a greater 'chimney' affect.

On my home server I blocked all the external holes in the case except
the air intake under the front panel and the PSU exhaust. I then
created air dams from polycarbonate sheet that ensured all the
incoming air went over the 3 hard drives and another over the
motherboard that ensured the air then went over the RAM and LSI
heatsinks, before being drawn out an over the PSU by the only fan in
there (in the PSU).

By sealing the case like that, ensured the air had to move *though*
the case, and not just round and round inside it and because of it's
height and general openness to airflow, convection would possibly keep
it cool even if the fan failed (in fact now the PSU only contains a
120mm slow speed fan as the PSU is an external 'brick').

So, say your amp had vents all the way along the top and the bottom
but a main board that covered most of the area of the inside of the
case. If you blocked off the middle section of the top and bottom of
the case and stood it on it's edge, convection would then cause air to
be sucked in at the (new) bottom of the case (on both sides), up
inside (behind the blocked off bits) and back out of the top? The
remaining open grill at each end only needs to roughly equal the cross
sectional area of space that is available inside the case.

In fact that's exactly what I have here with a TP-Link 16 port Gb
switch where there are only vent holes at the two ends and back and
nothing anywhere else (and no fan etc). I use it on it's end and just
added some extra feet to (what is now) the bottom to lift the end off
the work surface. It's also sitting beside a PC to I also added
bigger (stick-on rubber) feet to the bottom (now the side) so that it
ensures an airgap between the switch and the PC so that heat can
radiate out of the switch case and then air convect up the gap).

With some cardboard and tape you can experiment with your amp and see
if it feels hotter in use. ;-)

Cheers, T i m