RTX 3060 12GB Build for AI: Modern i5-10400 (16GB DDR4) vs. Dual Xeon E5645 (96GB DDR3)?

Hi everyone! I’m building a budget local AI rig and I'm torn between two options. Both will have an RTX 3060 12GB, but the platforms are very different:

1. Modern-ish: i5-10400, 16GB DDR4.
2. Old Workstation: 2x Xeon E5645, 96GB DDR3. (No AVX support).

My Main Goal**:** Developing a Local Voice Assistant. I need a pipeline that includes:

• STT (Speech-to-Text): Whisper (running locally).
• LLM: Fast inference for natural flow (Llama 3 8B or similar).
• TTS (Text-to-Speech): Piper.
• Secondary: Coding assistance (JavaScript, Python) and some Stable Diffusion.