Along with a CPU upgrade to take full advantage of a 4xxx card, or even a 3090 you would have to consider a quality PSU into the mix. RTX cards have high transient power spikes, and the higher level card, means the power spikes require a good quality PSU with a good bit of overhead to factor in the transient jumps.
Currently an RTX3090ti's can have up to 450w TGP. To get an appropriate PSU, you have to go 2.5 x the TGP. This means that you need a PSU of about 1200w to ensure that when the spikes occur your PSU can handle it (otherwise it trips the OCP and the PC may restart). It gets even worse with RTX4xxx series (or will be once we know the actual TGP of the new series.