[SOLVED] PCIe running @ x8 slows GPU by 50% from x16? Dumb Q?

hobkirk

Distinguished
Jan 7, 2012
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The #1 PCIe slot ("runs at 16x") in my "new" eBay GA-Z270XP-SLI MB does not work. But slots 2 & 3 (8x & 4x) do.
  1. My GPU is an MSI GTX 950, so it is already marginal for gaming.
  2. PC specs: PSU = Corsair CX430M, i5 6500, 8 GB DDR4 3200
Does "running at 8x" mean I will actually running at half speed compared to "running at 16x"?

Thank you for reading.