DAWWolfX

Antivirus is a need. Firewall is a need. And why? Because how many times - any user - has clicked an ad by mistake because the page moved the contents while clicking the desired link. Who does not use online banking and payments.
True, windows defender is good and propably the new firewall....but every hacker is hacking windows 1st then the 3rd companies antiviruses...And while you are nowadays playing in a WAN internet scheme you need to have all the protection you can get. Some people want to control kids times and sites too with them.
Everytime you open your pc nowadays...unless you dont have internet access at alll...you are at risk. Even putting a usbflash from school to your pc or from another friend you risk the "flue"!
You dont have to buy one, you can install a free version. BUT you need to have one.

This is the build 

If you're an experienced user the added security is similar to wearing a bulletproof west for office work. An adblocker will go a long way with the added benefit of reducing cpu cycles, instead of adding them.

Windows defender is good enough, never had any issue till now.

Windows defender does a solid job. Get like malwarebytes to be safe on top of that. 

If the case is under warranty, you can probably contact Phanteks for a front panel i/o replacement. 

2060 25% faster > 1660Ti 23% faster > 1060 6Gb.
 
1660Ti will be great upgrade from 1060 6Gb only for any of the 1660Ti custom card which not more than $300. Because you can get 2060 at around $350. So less than $300 1660Ti is good, but over $300 1660Ti is not worth it because there is 2060 there..

2060 is still ~10% faster than 1660ti. If you find a 1660ti for under $300, go for it. Otherwise I'd just spend the extra 12% more to get a 2060, take the extra 10% performance, and you'll have the RT and Tensor cores if Ray Tracing and DLSS ever do randomly take off and are good.

The obvious answer is no. I would prefer to buy new. 

To be honest I prefer the GTX 1070 for its 8gb vram. 
6gbs vram is getting to be the new minimum so if a 1070 can be gotten for about the same price I think it could last longer.
Having 6gbs vram as never been a issue with me at 1440p but games are getting harder to run. 
 

since you dont care about raytracing then the 1660 ti is a huge recommendation

I hear ya.. I asked questions and made sure their reputation was close to 100% with at least 50 reviews and no new accounts. 
 
The decent sellers on eBay won't really fuck you over because they (eBay) offer guaranteed money back whether the seller supports it or not. 
 
You can still find great deals with them on sale at places like Newegg every now and then. I got my liquid 64 for $499 on sale with 3 games. 

I prefer new as well, but the prices they're going for on eBay is just tempting lol. 
 
I actually bought a used Vega 56 Strix and had great luck with it before selling it to another member in this forum for $300.

Yeah I will be buying a card soon but I do expect prices to fluctuate as I have to wait for the money to come in. 

Easy. Used Vega 64 or 56. Either could beat both of those cards. 
 
I would get a Red Devil, Nitro+ or Saphire Pulse.. Awesome cards at great value.. 

i'd still go with the 2060 for a bit more, but it's personal perference really, since evga raised the price of their 2060 black from 320usd up to 350 now

If is is a $279 version, go for it.
They are on the EVGA website now.
https://www.evga.com/products/productlist.aspx?type=0&family=GeForce+16+Series+Family&chipset=GTX+1660+Ti
 

for 300ish? EVGA XC Gaming 2060 is 329.00 (or .99) now, and most likely will stay there for a while.  

yeah I had a GPU issue with an EVGA card... they sent me the wrong thing, a 1050 instead of a 1050ti. but in 15 minutes the whole thing was solved, and a new card was shipped to me in about 30 minutes. It arrived the next day, and i got to keep the wrong card. gave it to a friend cause I had no use for it at the time. but yeah, 30 minutes for the whole ordeal... 

if you're going midrange, you might want to wait for NAVI to be released... but that won't come in a EVGA flavor afaik

sapphire, xfx, asus, gigabyte, msi (not the armor) get a high recommendation from me on amd (asus arez and ROG are the same FYI)
 
EVGA, asus, msi (not armor for 10 series or earlier), zotac, pny and galax/kfa2 get a recommendation from me, especially EVGA as i personally have one
 
they can do in like 15 minutes somethimes, it's impressive

for 10 series or earlier. the rtx line is actually pretty good
 
yes, the costumer service has mixed reviews and some cards run pretty hot, but i personally don't have one. btw, i would avoid blowers (except if you can get a REALLY good deal on one).

I can vouch for zotac but not powercolor. Had a zotac gtx 970 for 3 and a half year and it ran great. My personal favorite are galax and asus. If you buy amd go for sapphire card. First video card i got was a sapphire r7 270 for 2 years as well.

The only "brand" I avoid is Asus, for the reasons listed here.
If you're going with nVidia, It's my belief that EVGA is the one to go for, as their customer service is really second to none. Multiple times i've contected them with a questions or issues (I've had to RMA a few things), and they've gotten back to me within 6 hours (20 minutes was the fastest), and when I had to replace a PSU, they had the new unit to my door in two days from the time the original message was sent (it also helps that I'm only about 40 miles from their RMA center, note)

I don't know much about the AMD side (the last AMD card I owned was the 7870 from above), but I know people often like Sapphire.
 

PowerColor had some serious DOA issues with the RX 480, but I'm assuming those were fixed with newer cards. I've never had a problem with a Zotac card, and as a result, I've never had to RMA one.