9800X3D is the best choice, but it is still hard to find it everywhere.

Get 7800X3D, a bit expensive than $400. https://www.amazon.com/AMD-Ryzen-7800X3D-16-Thread-Processor/dp/B0BTZB7F88?------123456890?7649-20

For $500 budget, get the AMD Ryzen 7 9800X3D.

I recently tested the i7-14700K with the 5070 Ti across several AAA titles, maintaining 120+ fps at 1440p in virtually every game with CPU utilization never exceeding 75%. For multitasking, the 14 cores and 28 threads handle rendering and streaming without breaking a sweat.

Ultra 7 265K.

Ryzen 7 7700X.

Any CPU works, just depends on how much you would pay.

Waiting for 9950X3D2.

TL;DR: Same boat. Trying to fit a capable platform into $500 for a 5070 Ti build is a nightmare right now. Ngl im dealing with this exact same issue. Trying to find a CPU that wont choke the 5070 Ti while keeping the total platform cost under $500 is basically impossible without a massive sale. I've been eyeing the AMD Ryzen 5 7600X 6-Core 12-Thread or even the non-X version just to save on power and cooling costs. The math just doesnt want to work out once you add in a decent B650 board and some G.Skill Flare X5 32GB DDR5-6000 CL30. Basically just commiserating here... the pricing is rough lately. If you spot a microcenter bundle or something let me know because im stuck too.

7800X3D or 9800X3D are both OK.

Waiting for 9900X3D.

9800x3d.

Intel Core Ultra 7 265K. https://www.amazon.com/Intel-Core-Ultra-Processor-265K/dp/B0DFK2MH2D?------123456890?7649-20

Any AMD CPUs are OK.