Weird iGPU artefacts with Buildzoid timings.

Hi! I've been running 6400mhz CL30 with Buildzoid timings, 1.30V SOC and 1.45V VDD, 2133mhz IF in 1:1 mode for a few months with a dedicated GPU with no apparent issues. Maybe some stutter every once in a while but I thought it was the game.

Today I sold the dedicated GPU in preparation of getting something faster as I upgraded my monitor recently. When I switched to the iGPU, lo and behold, horrible artefacting, flickering, static noise effect, on the dekstop. Running any game would instantly crash the system.

Some troubleshooting later, I nailed it down to my RAM overclock. EXPO (6000mhz CL30-38-38-96) runs with no issues. Buildzoid timings ONLY at 6000mhz and the iGPU goes bananas. No amount of vSOC, VDD, frequency, primary timings fix this issue. ONLY EXPO runs normally. I haven't tried EXPO timings with, say, 6400mhz or whatever, that will come tomorrow.

My question is: was I really ever actually stable? If a RAM overclock works fine with a dedicated GPU, but falls apart with the iGPU, was it actually ever good to begin with? Never had BSODs, WHEA errors, failed POSTs or anything like that, just the occasional stutter as I said, that I now think was actually a symptom of unstable RAM. But I never failed any memory test...

I don't know, it's really grinding my gears. What would you do? What would you change / try for timings, frequency and whatnot?

CPU: Ryzen 9 7900 RAM: G.Skill Trident Z5 Neo DDR5 32GB 6000MHZ CL30 Dual Kit - F5-6000J3038F16GX2-TZ5N Motherboard: Asus X670E-Pro Wifi

Thank you!