Budget: Around $600, can be more if it's a substantial difference
More specific use (what games, what programs): MHW, RE2/3
Planned time until purchase: ASAP
Do you have any specific preferred components?: No.
Zip code/location? (Shipping costs): 78109

My current issue with this PC is that I'm getting inconsistent frame rates even on the lowest settings for games. My current build specs are here (https://www.bestbuy.com/site/ibuypower-desktop-intel-core-i7-7700-16gb-memory-nvidia-geforce-gtx-1060-120gb-solid-state-drive-1tb-hard-drive-gray-black/6032004.p?skuId=6032004&cmp=RMX&extStoreId=144&ref=212&loc=1&gclid=CJDi0PrFldoCFQZWfgodZp0Bmg&gclsrc=ds)

I know very little about computers, but I believe part of the issue is my graphics card only has 3GB, so I'm hoping I can find an upgrade that will be compatible with what I already have.

If I'm missing any key information, I'll update relatively quickly. Thanks in advance.

What wattage is your PSU ?
and your probably correct about the vram.

Should aim for a 2060 super/2070 super

Looks like 500.

It should work but I'm always cautious with off brand psu's so can you make sure its 80+ bronze unit and if its not consider replacing it as well.
If you end up replacing it your goal is 80+ 600 watts and its up to you if you wanna pay more for semi/full modular unit.

Unfortunately not, but I wouldn't want to risk it anyway. If I have to upgrade the power supply, I may as well go for the 2070.
Not entirely sure what the differences are between cards/brands. I was going to just get one straight from Nvidia's site, but their brand is out of stock. As for the power supply, I'm even more in the dark.