Upgrade to AMD 5900X CPU or not?
TL;DR version up front - I have the chance to upgrade to a new unused Ryzen 5900X 12-core CPU at MSRP $549. I would need to buy a motherboard to move to an all AMD build (maybe an ASRock Taichi RAZER Edition X570 for $380). I'd then move my 32GB G.Skill 3600MHz Trident Z RGB Ram, Corsair H115i AIO, and 2TB Evo Plus SSD over to the new motherboard. Taichi looks like it has all the RGB and fan headers I need, and I could add Thunderbolt later if needed (has TB header). The Wifi 6 is also upgradable to Wifi 6E via a new key E card. I can live without thunderbolt as I'm not using integrated graphics and my only Thunderbolt RAID0 has 5400 RPM HD in it and works with USB 3.0 too.
So here is the situation. I am currently running an i7-11700K overclocked on a slightly used MSI MEG Godlike Z490 motherboard and Trident Z 3600MHz RGB RAM, which supports PCIe Gen 4.0 on the PCI card slots, but not on the M.2 slots. I can buy a Gen 4 M.2 SSD and install it in an included PCIe 4.0 daughterboard for Gen 4 speeds, but I don't run the daughterboard since it could obstruct some airflow to my Nitro+ 6900 XT graphics card. I just keep my Gen 3 SSD in one of the three M.2 slots on the motherboard running at PCIe 3.0 speeds.
When I was almost finished building my PC at the end of April I didn't feel that it was worth it to sell my lightly used $400 Z490 and spend $500-900 on a new Z590 board with all the features I wanted, just to get new full PCIe Gen 4.0 chipset when it would not make my 11700K faster, although I could get 2x the SSD speed with a Samsung 980 Pro. I'm already seeing fast 3490 mbps read and 3300 mbps write speeds my 2TB Samsung 970 Evo Plus and had returned my smaller 1 TB 980 Pro without ever using it (same $200 price for either).
I paid $400 for my used Z490 back in March when I started working on the build (MSRP $750), and it came with a 10700K for an additional $300 which I sold for what I paid to buy the 11700K. As I mentioned, it does have some limited PCIe Gen 4 support, plus tons of front and rear USB ports including Type-C 3.2 Gen 2 10gb front panel, two Thunderbolt 3 on the back, integrated WiFi 6, with OLED status panel dynamic dashboard and RGB. I also really like the upgraded ESS DAC output on the front panel, which is better than the RealTek audio output on the rear. It also supports 10 Gbps network once I upgrade the house wiring and router later. When I started the build, the 11900K and 5900X or 5950X were only a dream, and could not be found).
Anyway, just last month I passed on the chance to switch to 1 month old AMD 5800X CPU slightly used for $400. At the time it wasn't worth it to have to also buy a new motherboard for the switch when 5800X is only 5% faster than my 11700K without integrated graphics. If I get the more attractive 5900X then I'd have to sell both my 11700K and my Godlike Z490 to help fund my new AMD motherboard, and I don't want to get robbed by eBay crooks. Sp there is a small chance I would send it to my brother with an Enermax Liqtech II 280 cooler and 3200 Mhz RAM that I have laying around, so he could upgrade from a 4th gen i7 8-core and I could avoid eBay crooks. I already gave him a GTX1070 last month, and he is poor and would not be able to pay me anything.
But the 12-core 5900X is more attractive to me than that 5800X which I passed on, and it's making me think about the switch and turning on SAM with my 6900XT. The 11700K has been working well for me, but I've never used the integrated graphics of the 11700K, and I already have an RX 6700XT and GTX 1080 as spare graphics cards should my Sapphire 6900XT die. So I'm not forced to stick with Intel just for integrated graphics as a backup.
Sorry for being so long winded, but would it be a good idea to take this 5900X for $549, buy a new mobo, and sell or give away my old CPU/mobo to get more out of my 6900XT and to more future proof my build?