Question about Icy Box IB-PCI209

Sorry, but no. The Icy Box has a SATA interface and cannot read M.2 M Key.
I also fell in...
Greetings Syranisi

I was able to install an MVME M.2 SSD in the bottom slot without having to connect the satellite cable. I don't know if a Gen.4 will work. It probably does, but with a considerable loss of speed.

Yes... agree with empty! The lower slot is connected via PCIe 3.0 x4. With PCIe Gen3, 128b/130b encoding was introduced, with four lanes this theoretically results in up to 3.94 GByte/s and in practice the fastest PCIe Gen3 x4 SSDs deliver up to 3.5 GByte/s. I have installed a GEN3 M2 SSD on my ICY BOX IB-PCI209, which delivers approx. 3000 MB/s and approx. 2200 MB/s when writing. A GEN4 M2 SSD is actually an unnecessary waste of money on the ICY BOX IB-PCI209. The GEN4 M2 SSD must be installed on a mainboard with an AMD B550 or AMD X570 chipset in order to deliver the full performance. If anything, I would recommend a Corsair mp600, GEN4 M2 SSD! Corsair MP600 (1000GB, M.2 2280) see test https://youtu.be/Z4wXSF8Uwj...

The lower slot is connected via PCIe 3.0 x4, the upper slot only via SATA. In the lower slot, the Gen4 SSD only runs with Gen3. Almost all M2 SSDs use 4 lanes, i.e. up to 4GB/s with Gen3. You will hardly notice the loss in performance, the fastest Gen4 SSDs currently barely manage 5GB/s and only for special accesses for a limited time. If you want to boot from it, your mainboard must support it, you should clarify this beforehand.