GPU & CPU usage go down overtime, being utilized fully only upon startup

Apr 21, 2018
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Specs
GPU: GTX 960
CPU: i5-7600k
RAM: 2 8GB HyperX 2133mhz
HDD: 2 1TB SATA 6GB/s
MOBO: MSI H110M Pro-VD Plus

When I startup Warframe upon startup, usage goes to around 80% on both GPU and CPU and I get a stable ~144FPS, but overtime, it lowers and keeps lowering until GPU usage is at 2%, CPU usage at 20% and I have 5 fps.
When I tried to get more data in R6:S, it only loads up until "Creating Squad" and crashes

PCIe power management is off in power settings
Power settings are on performance
Removed GPU drivers using DDU and reinstalled latest

EDIT April 23, 2018 "2 GB HyperX"