Is still worth "maxing out" am4 in late 2025?

Hello everyone! I hope you all doing great this time of the year :)

I’m a CompSci student looking to build a local rig for running larger LLMs (like Qwen Next) and doing some ComfyUI workflows. I currently have a single-GPU setup, but I have a specific upgrade path available and I want to know if the PCIe lane benefits are worth the hassle.

My current setup:

• Mobo: Gigabyte B550 Gaming X V2 (Second slot is chipset-limited, likely slow)
• CPU: Ryzen 5 5600X
• RAM: 128GB DDR4 (Ripjaws V 2666 OC'd to 3200)
• GPU 1: RTX 5070 Ti (16GB VRAM)

I can get a bundle of an Asus ROG Crosshair VIII Formula + Ryzen 5950X for just $370. Also I want to move to the X570 board to use PCIe bifurcation (x8/x8) and add a second GPU:

• GPU 2: RTX 4060 Ti (16GB) connected via a riser cable.

My Questions:

1. Inference Speed: Will running the 5070 Ti and 4060 Ti in x8/x8 mode (PCIe 4.0) strictly beat my current setup?
2. Model Targets: With 32GB VRAM + 128GB System RAM, is this enough to run Qwen-72B or Llama-3-70B at decent speeds (e.g., Q4_K_M) with some offloading?
3. Value: As a student, is dropping $370 + cost of the second GPU (~$450) worth it over just renting a runpod, or will this hardware last me a while?

Thanks for the help!