At the end of my wits - Bottleneck Edition

[kolunez]

Specs:
H61M-DGS
i5 3570
R9-280x
8GB 1333 Corsair RAM (7-7-7-20 timings)
Windows 8
Corsair CX500 PSU

Problem: In all games I've tried (Far Cry 4 / GTA 5 / Wolfenstein NWO and etc.) the FPS + GPU Usage takes a dive (to around 20-30's) in certain areas. The other times it's pretty playable at 60 FPS, but when the FPS takes a dive (and this coincides with low GPU usage like 50%) it's not playable very well.

I've tried different RAM, I've flashed my BIOS to the newest edition, I've tried installing and reinstalling Windows 10 / Windows 8.1 / Windows 8. I've installed different versions of the AMD Drivers. I've played around with CC settings etc.

Before this I had an i3 2100 + GTX 560Ti that exhibited the same symptoms, but to a much greater degree. At first I upgraded to the R9-280x but GTA 5 was unplayable with the i3 I had, so I upgraded to the i5 and then it was playable but still hit the low usage/fps combo.

So that leaves my MOBO as a potential problem. Could the fact that I can't set XMP memory profiles be the reason for this? i.e my RAM not being configured properly in the BIOS? That's the only idea I have left now.

 

[Calvin7]

R9-280x
Minimum System Power requirement (W)
750W

Extension Power Connector
One 6-Pin and One 8-Pin PCI Express Power connectors

 

[kolunez]

R9-280x
Minimum System Power requirement (W)
750W

Extension Power Connector
One 6-Pin and One 8-Pin PCI Express Power connectors

I thought that 500W was enough for most systems though... and I do have my PSU connected to the GPU using 1x 6 pin and 1x 6 pin + 1x 2pin adapter.

 

[kolunez]

Update:

Installed a new MOBO. Same exact problems. (also reformatted)
Got new XMP Ram. Same exact problem.

At this point I have basically built another computer minus the PSU and hard drives (1 SSD and 1 HDD) and still have the same issue.

I don't know what to do anymore honestly, I might buy another PSU at this point but I don't see how that can logically fix my issue.