I wish someone bothered with modern bifurcation and/or generation downgrading switches.

For homelab purposes I'd rather have two Gen3 x8 slots than one Gen5 x4 slot, as that'd allow me to use a (now ancient) 25G NIC and a HBA. Similarly I'd rather have four Gen5 x1 slots than one Gen5 x4 slot, as Gen5 NVMe SSDs are readily available and even a single Gen5 lane is enough to saturate a 25G network connection and it'd allow me to attach four SSDs instead of only one.

The consumer platforms have more than enough IO bandwidth for some rather interesting home server stuff, it just isn't allocated in a useful way.

gen5 does not exist in x1, that is IP issue.

other issues you mention are only "firmware disabled". chipsets are capable of bifurcation, so maybe try to visit some chinese / russian firmware hacking forums... i found out that server and consumer icelake generation is fully "cracked" open on there for years. there you can find all sorts of "BIOS" generators which can generate "BIOS" of your liking.

cheapest way to do what you describe (after fiddling with your "BIOS", "firmware") is by buying NVME HBA, which are just renamed PCIE switch ICs.... ;) brand name PCIE4 switch can be bought for 1000-1200 dollars retail, it will allow you to bifurcate to x1 but im not sure about prices for pcie5.

or if you want more costly but out of box working device try looking at [ https://www.h3platform.com/product-detail/Topology/24 ]

and do not forget that newer intel PC have USB with 40 gbps... so do you really need 25 gbps eth ? linux / BSD does not care what you transfer over USB (ETH/ipv6 encapsulated in USB)...

EDIT: you can buy HBA with 8 x4 connectors. this HBA/switch is connected to your pc over PCIE4 x8... 8 times 4 = 32 =x8 port... so you get x1 speeds, you can connect only one lane on x4, etc. out of box thinking.

installing BIOS from chinese / russian forums might be the last thing one would ever want to do, though

of course, it was more like "go ask to countries which does not care about IP/NDAs" they can post it freely. you can always copy what they do even without using whole code/image/bin.

I'll host them on a US/EU forum. Better now?

>broadcom rug pulled the PCIe switch market.

What does this mean? Did they jack up prices?

Avego wanted PLX switches for enterprise storage, not low margin PC/server sales.

Same thing that Avego did with Broadcom, LSI, Brocade etc... during the 2010's, buy a market leader, dump the parts that they didn't want, leaving a huge hole in the market.

When you realize that Avego was the brand produced when KKR and Silver Lake bought the chip biz from Agilent, it is just the typical private equity play, buy your market position and sell off or shut down the parts you don't care about.

When the LSI buy happened, they dumped massive amounts of new, but ptior gen stock into the distributor channel, then immediately claimed them EOL.

Scumbags.