I do not need or want a server system - they are too noisy to run in a home environment, and generally use far too much electricity too (making all that noise!).  As for a NAS, there is no point in having a NAS when you have a PC that runs 24/7 - you just put more and/or bigger drives on the PC.  It is cheaper that way than a separate NAS.  So what I want is a new desktop motherboard that will do everything that my old one does, but also has the latest technology and will run Windows 11 (and 12 and 13) well for the next 10 years.  In the past, it was not difficult to find such motherboards - they were generally at the higher end of the price range, but when I have bought good motherboards, they have lasted very well.  This time, there is nothing at all that I can find that has 5 PCIe slots and 8 SATA ports and also does PCIe 5.0.  Even the grossly over the top $2000 motherboards do not have enough PCIe slots.  It just seems to be something that their designers have forgotten about - each slot only accommodates one physical device!  More cards needs more slots!

@richms: If you could point me to a $700 motherboard that does PCIe 5.0 and has the slots I want, then please do.  The $2000 motherboards I have looked at do not have that many slots.  With PCIe 4.0, yes, you can get the slots still, but so far, not with PCIe 5.0.

I was aware of the M.2 to SATA x 4 boards - they are a decent option to get more SATA ports, but since I read the reviews on them and discovered that they are bandwidth limited when all of the SATA ports are in simultaneous use, I decided a better option was probably a SAS card with SATA cables.  Especially since I already have such a SAS card in the Windows box similar to the one @rb99 pointed to.  Mine is an IBM rebrand of an LSI SAS2008.  It has 8 SATA ports, 4 on each SAS connector, and uses a PCIe 2.0 x8 interface, so it uses up a x8 slot, but it was very cheap.  It is now possible to get much more in a SAS card, using PCIe 3.0 and 4.0 so it does not need as many PCIe lanes, but the prices are steep.  I may invest in one if I ever need to, but for now the LSI SAS2008 is fine.

I am considering reducing the number of drives in this PC, as some are very old and small now (2-3 Tbytes).  It does have several bigger ones though, 8, 12 and 16 Tbytes.  My MythTV box has 2 x 18 Tbytes now, and 20 Tbyte drives are available.  So I could replace the 4 small drives with one big one now.  But eventually, I would expect to need over 8 SATA ports again.  And I need to wait until I have a new motherboard before I can replace the old drives, as the BIOS on the old motherboard is very cranky when it comes to booting NVMe and needs to do it with old partitioning, not GPT.  It was never designed to boot NVMe, so is is fairly miraculous it does at all.  I have to be able to boot to a secondary Win 10 boot partition to recover from the frequent crashes where the main Win 10 GUI just locks up.  And the secondary boot works off the oldest 2 Tbyte drive, and is dependent on that drive being on the ASMedia controller, as the BIOS refuses to boot anything on the SB950 chip while an NVMe drive is installed.  Arrgh!

@surfisup1000: I have tried Win 11 - I have it on my new laptop.  I did not like the way it worked, so I just installed Stardock's Start11, which I already use on Win 10:

https://www.stardock.com/products/start11

That way I can choose to use a Win 7 style interface, which I prefer.  I also use Stardock's ObjectDock for starting things I commonly use:

https://www.stardock.com/products/objectdock

That means I do not use the main Windows menu much at all.

With those add-ons, Win 11 is fine, just as Win 10 was.