Obviously you didn't benchtest your hardware. Once you install it in the case, all bets are off & troubleshooting can be difficult. I suggest you pull the motherboard from the case & test it, which is what you should have done in the 1st place.
"Help" Why don't you help us by giving some details about your new build-it is impossible to give anything but very general recommendations without knowing the Mboard, psu, cpu, RAM-well, you get the idea.
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