RAM Upgrade Dilemma: 64GB Dual-Channel vs. 32GB Quad-Sticks? Help Me Decide!

Hey everyone! I need some advice on upgrading my RAM. Here’s my current setup:

  • 1x 32GB D50 stick (2990 MHz)
  • 2x 8GB D50 sticks (2666 MHz)

I want to upgrade for better performance while keeping at least 32GB of RAM total. My two options are:

  1. Add another 32GB stick (same 2990 MHz) for 64GB total (2x32GB in dual-channel).
  2. Add 2x8GB sticks (same 2666 MHz) to fill all 4 slots for 32GB total (4x8GB).

Cost difference:

  • 32GB stick: ~$70
  • 2x8GB sticks: ~$55

Priorities:

  • Performance matters most (gaming/productivity).
  • I rarely exceed 32GB usage, so capacity isn’t critical, but 64GB is a "nice-to-have." for my development work as well (can be ignore).

My concerns:

  1. Mixing speeds: My current 32GB stick runs at 2990 MHz, but the 8GB sticks are 2666 MHz. Which combo will be faster for gaming?
  2. Dual-channel vs. 4 sticks: If I go with 4x8GB, will it still run in dual-channel (not quad)? Does using all 4 slots impact stability or speed?

TL;DR: For a performance-focused setup, should I prioritize:

  • 64GB (2x32GB) at 2990 MHz (but $15 pricier)?
  • 32GB (4x8GB) at 2666 MHz (cheaper, but possibly slower/faster than the 1st option)?

Thanks in advance for your expertise!