The Intel Core Ultra 7 265K wins in 12 out of 16 comparable specs, with 1 tie. Its biggest advantage is L2 Cache (500% better).
Ryzen 5 8500G wins in 3 specs (Max Turbo Power: 74% better).
Recommendation
Choose Core Ultra 7 265K if you want the best overall performance — especially l2 cache.
Choose Ryzen 5 8500G if max turbo power matters more to you.
