Question Can't enable X.M.P. on Gigabyte Aorus z790 PRO x

[Biro2001]

So I put together another pc build, and after making sure that windows is installed correctly I ran into some weird problems. I can't seem to get past Bios when enabling XMP memory profile, the system doesn't boot after I switch Xmp on and I can't reach into the Bios anymore, only if I clear CMOS. I have four sticks of ram (DDR 5 - 5600Mhz corsair vengeance) but oddly enough they seem to run at 4000mhz (not even 4800mhz as it is advertised) .
I tried to run one stick (each) and every time it seemed to actually run at 4800mhz, but alas if I install all four sticks, I get the 4000mhz problem.
To keep in mind I actually tried to enable XMP only with one or two sticks of ram installed, but still can't get to boot (only the black screen remains). I have to send this soon to the customer so I would like to at least understand what is going on with the system, and before you tell me about the compatibility or the fact that I bought 4 sticks and so on, keep in mind I buy and build stuff that people buy so my customer wanted 4 sticks I bought 4 sticks, and they were compatible I checked. Here is the list of components:
i7 - 14700Kf / 128 Gb ram (4x32 ddr5 5600mhz) / Motherboard Gigabyte Z790 Aorus Pro X / Cpu Cooler Corsair h150i link / Psu Corsair rm 1000e / Ssd Samsung 980 pro 1tb / Gpu Nvidia 4060ti Msi dual.

 

[Lutfij]

Try two sticks of ram at the advertised ram frequency. What BIOS version are you currently on for your motherboard?

 

[Biro2001]

Try two sticks of ram at the advertised ram frequency. What BIOS version are you currently on for your motherboard?

Hi! The bios version is last version (F4 in this case). I can run 2 sticks of ram but even if it shows at 4800mhz (I have the kit that can support 5600mhz). So basically I didn't solve the problem as even with 2 sticks I can't seem to enable xmp without getting a black screen