Looking at the options ....
Budget
Sell the 580 = -$100
Grab a 1660 = $230
Net cost = $130 ....23% performance (26% over OC'd Nitro when both cards OC'd)
Each 1% increase in performance is costing you
$5.00
Budget
Sell the 580 = -$100
Grab a 1660 Ti = $280
Net cost = $180 ....48% performance
Each 1% increase in performance is costing you
$3.75
Budget
Sell the 580 = -$100
Grab a 2060 = $350
Net cost = $250 ....64% performance (68% over OC'd Nitro)
Each 1% increase in performance is costing you $3.68
Budget
Sell the 580 = -$100
Grab a 2070 = $500
Net cost = $400 ....89% performance
Performance ROI =
$4.49
The 2060 has the lowest cost per unit gain in performance..... not to mention,
https://tpucdn.com/reviews/Intel/Core_i5_9600K/images/relative-performance-games-1920-1080.png
Your 8400 delivers 96.9% of the fastest gaming CPU available at 1080p.... so don't see any room for significant impact on the CPU side.
Also, basing your evaluation "well the card is overclocked almost to next tier card" is a fool's errand because it ignorees that facts that a) every other card is able to be overclocked too, and b) since your current card is AMD, you have to recocognize that AMD very aggressively clocks the card in the box, which doesn't leave as much headroom left ...
Sapphirre 580 Nitro - 5.0% over reference stock 580 fps in TPUs overclocking test
MSI 1660 - 16% over reference stock 1660 fps in TPUs overclocking test
MSI 1660 Ti - 16.3% over reference stock 1660 ti fps in TPUs overclocking test
MSI 2060 - 12.2% over reference stock 2060 fps in TPUs overclocking test
Since you had indicated that the 2060 was too expensive, I would suggest postponing the purchase a bit until you can save more money. In the long run, the 2060 offers the best bang for the buck by a considerable margin over the 2070 and 1660 and still has the edge over the 1660 Ti. Consider also that due to changes in market share in the last month, I expect AMD will be cutting prices which in turn will force nVidia to do the same. Most folks I know are waiting till May in anticipation of same, and here in US anyway also hopping they at least switch the tariff situation .... if there's going to be a tariff, it should be on assembled PCs built in china, not parts shipped here and assembled by US labor.
