I already have an HTPC that is completely passive cooled. It has a Intel DH57JG motherboard with Core i3 530, 1.25v RAM, and 0.2w SSD, PicoPSU 90w. With the low voltage components, it idles at around 20watts and about 30watts for Windows Media Center usage. Temps are around 36C idle, 45C HTPC load in a 78-80F ambient environment.
The problem is that the DH47JG is emitting very high pitched frequency noise. It is very audible in a quiet room and extremely annoying. I've tried to locate the source on the motherboard (using the tube ear trick) and it looks like it's coming out of 3 coils OR the processor itself (not sure). The power bricks also emit high pitched frequency noise BUT those are not audible. Even the monitor emits frequency noise but it is not audible.
I'm thinking about rebuilding the HTPC with a better motherboard and case instead of this POS Intel board. The powerbrick for the PicoPSU is crackling (somewhat audible), I've tried several other power bricks (EDACs etc)...those are all somewhat audible. So I like to replace the PSU and go with a full sized passively cooled PSU (Seasonic X400 series looks good).
These are the components I have:
LIAN LI PC-V351B case - The main issue with this case is that the PSU is right over the CPU...since the PSU and CPU are both passively cooled, could the PSU overheat? Also the only fans are in the front (dual intakes)....I can replace those with S-Flex BUT it was a stupid decision on Lian LI to go with all front intake instead of rear exhaust. Is there any better cases? (It has to be horizontally placed and able to fit in a shelf (21" depth, 20" width)
GIGABYTE GA-H57M-USB3 motherboard - This is a mATX board, I really want to use a mini ITX but I think that because of the miniaturizing of the components required for ITX, it can be guaranteed to produce high pitched frequency noise. Do you think this one will produce high pitched frequency noise OR do you have any other recommendations? I've always bought Gigabyte motherboards cause they have solid state caps and really good build quality (backup + recovery bios, safe boot after config error etc)
Seasonic X400 - Passively cooled PSU, is this a good choice?. I think I have a spare Corsair 520w but not sure if that is passively cooled (really good PSU).
Heatsink - Not sure what to get. It has to be large enough to dissipate heat passively yet be low profile due to case limitations. Not sure if a Ninja mini will fit in this case?
The primary goal is to get rid of the annoying high pitched frequency noise.
On a side note: Back when Intel's flagship processor was the Pentium 4 and Pentium M for laptops, I never had frequency noise. Starting from the Core Solos (yonah), there were all sorts of complaints about high pitched frequency noise (it's getting worse with each new platform). Is this due to cost cutting by manufacturers or bad design? Maybe it's related to energy saving features starting from the Core Solos? If it's due to energy saving features, isn't there way to prevent components from producing audible frequency noise? Motherboard manufacturers blame Intel SpeedStep, Intel blames the Motherboard manufacturers.