Earlier quoted context omitted.
Who said anything about cutting GPU performance? Also your comparisons are quite poor... 2600 shouldn't even be in the running here, the 3070 would be held back from doing the thing it does best, high FPS 1440p (in actual games mind you, not just CS:GO)
I mean, you said I should waste my money on a CPU upgrade that would make no difference in 1440p gaming. That's money I can't spend on a better GPU, which would make a difference in 1440p gaming.
My suggestion over the included build is spending $10 more on the build and getting a 10600K.
Silicon Lottery has found 100% of 10600ks will do 4.7 Ghz sustained all core.
Even at that number it will easily out perform a 3600 in a meaningful way. Over 70% of them do 4.9 Ghz which where it starts to reach i9 levels of performance in gaming by the way...
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And the cherry on top over the 3600 is you can actually buy the i5 outside of Microcenter. Microcenter is the only place carrying the 3600 for $180... but they also have 10600k on perma-sale for $250.
Meanwhile outside of Microcenter the 3600 is rarer than hen's teeth while the 10600k is widely available at $270. I happen to have 5 microcenters within an hour or so of me, but most people don't have that luxury.