This is a weird one for me.

I recently built a new machine. I'm running the ROG STRIX X299-XE GAMING motherboard with an i7-7820X, 16GB (2x8GB) of Corsair Vengeance 3000MHz LPX DDR4, and a Samsung 960 EVO 500GB NVMe M.2 SSD. I'm using the Corsair Hydro Series H100i v2 AIO cooler for the CPU. I even installed the little VRM cooling fan that Asus included in the XE version of the motherboard.

The machine runs cool and stable. BUT....

When I use the EZ Tuning overclocking utility within BIOS my ethernet download speeds drop significantly. I have Verizon FIOS gigabit service using their "Quantum Gateway" router. I'm directly connected to it using a good CAT 6 cable. Without the overclock, I get consistent 800+ Mbs, both up and down. If I use the EZ Tuning overclock, my download speeds drop to 100-150 Mbs. Strangely, my upload speed remains around 800+ Mbs even when overclocking.

This is completely repeatable and consistent.

The EZ Tuning automatic overclock settings are as follows:

(1) AI Overclock Tuner set to XMP

(2) DRAM voltages up to 1.35

(3) Core ratios increased to 43 (for most cores) and 46 (for Cores 1 and 7) .

(4) DRAM CAS# Latency to 15

(5) DRAM RAS# to CAS# Delay to 17

(6) DRAM RAS# PRE Time to 17

(7) DRAM RAS# ACT Time to 35

I've updated the Intel network driver to the latest version from Intel's site (since they don't seem to auto update). I haven't had the time to experiment with manual overclocking settings. I'm guessing that the DRAM timings are probably creating a conflict with the Intel drivers, but wanted to get some thoughts and ideas here before I continued to bang my head against the wall.

So, anyone have any thoughts?