Try slightly under-clocking your GPU core and Power Limit. (using MSI afterburner)
Try disabling any unused devices (sound cards, USB devices etc)
Try upping your TDR delay via registry. (https://docs.microsoft.com/en-us/windows-hardware/drivers/display/tdr-registry-keys)
"TDR stands for Timeout Detection and Recovery. This is a feature of the Windows operating system which detects response problems from a graphics card, and recovers to a functional desktop by resetting the card. If the operating system does not receive a response from a graphics card within a certain amount of time (default is 2 seconds), the operating system resets the graphics card. "
if you need more help with any of that just ask and ill see what I can do.
Sometimes too many Bio-Blast nids spawn. like whole lines of them cued up.
It's all good but sometimes its just annoying, probably also due to the sound also being WAY to loud at distance etc.
About the Giants, can you give them a different icon on the RADAR please. maybe a Gold star or something. when they spawn right behind you and insta-frag you its annoying and cheap tactic.
At least if there was a RADAR marker you would at last have some knowledge that there is one right behind you - OR - a sound effect of crumbling rubble and rock as they tunnel up through the ground. That would give you some warning.