Long time passed as my RAM was stuck @customs
and I was also waiting for the CPU longer - The CPU was the last part of the puzzle, but was worth it, via local store/supplier with warranty.
While my original PCI-E cards composition plans had failed(As 2.5 desktop slots are 3 server slots due to standard clearance between slots on server MB), GPU is again in the top slot, leaving me only 2 extra slots, which I've used for my RAID card and USB controller.
I've forced to remove my Intel X710 dual port NIC, but its fine - The built-on Broadcoms doing well and Hyper-V V-Switch was easy to reconfigure to use them.
The BBU for RAID card is located after the USB card in the area not occupied by MB - SO the case just "holds it".
The extra cooler for a raid card v-mounted here, instead of being under the RAID card, due to lack of space, and was later removed(The picture is before removal) due to motor noice of central fan.
I've bough the Seasonic TX-1600 PSU at the end and built the system with it(After testing it with a tester from AliExpress xD).
I have plenty of USB ports for my needs(PCI-E card 5 ports + 4 built-in + 2 front + [1->4] hub for devices not using much power and needing much bandwidth(USB DVD Writer, WD Elements HDD with own Power Supply, APC UPS USB mgmt port))
Memory bandwidth during memtest with 6 channels was 46G/s, while my Ryzen 3900X had "only" 12G/s.
Installation was painfull, especially finding the T20 torch of sufficient length to mount the CPU(With shorter ones the radiator cut my fingers, forcing taking means to avoid blood spilling on the mobo), and didn't allow to put enough force to close some of the torches.
Making one of sufficient length from multiple unrelated parts in the house I've managed to complete the installation.
The CPU and RAM booted just fine during the first start and the only problem I have to solve is setting up fan thresholds via ipmitool, as it constantly ramps-up, then slows-down the CPU heatsink fans. Funny thing is then it slows down those fans it become quite silent.
Extra discounted RAM modules are on "backorder" but I don't care about them currrently.
3DMark gave me the "Mystery Machine" achievement - Looks like no one plays on Epycs
this heatsink is for bottom to top.
I had the same concern as right to left is the best in my cooling setup, but due to form of the SP5 socket(Not a square) it can't be rotated 90d, as I ended with "bottom to top" configuration,
which also fits weel as I've had exhaust from my AIO radiator on top before and it has good clearance from bottom(Due top DIMMS) to suck the air coming horizontally from the right, before it gets exhaused on the left.
They say delivery failed due to not having a 9 digit zipcode, and will not refund my purchase price or reship.
Ouchhh, hell.... Was it the same seller I bought from?