Hello,

Before a single MSI RTX 3060 LHR v1 run smooth mining ETH at 49MHs (470.05 nvidia driver + hdmi dummy plug windows 10, t-rex miner) with:

Motherboard: MSI Z390 A PRO
CPU: Intel G5400 Pentium Gold 3.7Ghz Socket 1151

Since it has 6 slot PCIE, i want to use it for another rig.
So i found a cheap mobo:

Motherboard: GA-H61M-S1 rev 3
https://www.gigabyte.com/us/Motherboard/GA-H61M-S1-rev-30/sp#sp
CPU: Intel Core i3-3240
https://ark.intel.com/content/www/us/en/ark/products/65690/intel-core-i33240-processor-3m-cache-3-40-ghz.html

But after it arrived, i swap the motherboard and cpu, the speed just 26 MHs.
No setting change.
In the Intel i3-3240 spec page said it has PCIE Gen 3.

Is it a stupid buy?

Any help would be appreciate.
Thank you in advance