EXTREMELY confused about which build to buy for 1080p gaming. PLEASE HELP.

In the first build, change the RAM to 2666mhz or higher and ditch the cooler. You are all set. If you have money left, then get another 8gb RAM and/or SSD.
In case these are prebuilds, get these specs modified.

Yup, second build is fine as it is, if you dont wanna ditch the cooler. The stock cooler is not as bad as you think unless the chip is OCed.

Go with the RX580 and take advantage of your freesync. That is worth it. Build the best system you can around the RX580. The Intel cooler is fine if not overclocking....it will even overclock some. Intel doesn't heat as much. You may even consider an AMD Ryzen CPU or one with the wraith cooler included to save some cash.

Go with the RX580 and take advantage of your freesync. That is worth it. Build the best system you can around the RX580. The Intel cooler is fine if not overclocking....it will even overclock some. Intel doesn't heat as much. You may even consider an AMD Ryzen CPU or one with the wraith cooler included to save some cash.

In the first build, change the RAM to 2666mhz or higher and ditch the cooler. You are all set. If you have money left, then get another 8gb RAM and/or SSD.
In case these are prebuilds, get these specs modified.

Yup, second build is fine as it is, if you dont wanna ditch the cooler. The stock cooler is not as bad as you think unless the chip is OCed.

Stock cooler will hold turbo boost for i5 8500 fine. No need for aftermarket coolers because those chips are locked anyway, meaning, they can't be overclocked. If anything, stock cooler can get loud, but it gets the job done.
As for the builds, 1st one would go nice with a freesync monitor, they are cheaper than gsyncs, so can save a buck there in the long run.
Overall, 2nd build is better, because it has higher speed ram and a Z370 mobo which is more upgrade-proof for the future.

Can't go wrong with either one, but I'd choose the 2nd as I mentioned above just for the upgradability options. Other than that, both will game fine at 1080p.

What are the actual specs of the Freesync monitor? If it's really fast you may want to consider a 'long game' and build with an eye on future upgrades; Rebalancing the current build with a lower spec GPU in order to have faster memory will mean lower FPS now but will allow that fast display to run better when you upgrade the GPU later.

Overall the RX580 is faster than the GTX1060, although in some games the reverse is true, but, overall the RX 580 is the faster option.

Intel systems are less sensitive to memory speed than the current Ryzen parts from AMD, but DDR4 2133 is really going to hamper the system, DDR4 2666 is a nice compromise between 2133 and 3000+ speeds.

The stock Intel cooler isn't a top line part but it's adequate for the job, if money is very tight, drop the FrostFlow and divert the cash into faster memory, you can always add a batter cooler later, but whatever memory speed you choose now is the speed you'll upgrade with later and DDR4 2133 is really too slow for a dedicated gaming rig.

There's little need for a 'Z' series motherboard in this build, unless you need a feature or features this chipset offers you might be able to use a cheaper 'B' series MB and put the money saved, again, towards faster memory.

It is quite possible to use a Freesync display with an Nvidia card, just use the 'Adaptive' option in the vertical sync section of the control panel, as long as the games run over about 48FPS I doubt you'll spot much difference between this option and either Gsync or Freesync.

Me' Id go for the Nvidia build, it's not quite as fast in the GPU but has faster memory for the future.
If possible, try to rebalance it, maybe go for a 'B' series MB along with DDR4 2666 memory, drop the CPU cooler and see if you can squeeze a RX580-or even a Vega 56-into the build.

For an Intel chip, the ram speed gain would be negligible in real world use. It's just nice to have, so to speak.

Personally, I'd go with then RX580 build to stick with Freesync but drop the cooler and put the money into faster memory, it'll be cheaper in the long run.
Yea, the stock Intel cooler can get annoying but a cheap air cooler like the Hyper 212 series or Cryorig H7 will cure that easily enough and upgrading the memory with an additional 8Gb will be far les expensive than E-baying 8Gb of slower RAM and replacing it with 16Gb of faster memory later.

EDIT: Faster memory DOES make a difference, particularly with minimum frame rates.

There is something I forgot. If your monitor is 144Hz then Freesync will be very useful as with an RX580 you'll get in the 40-100FPS range for most games. Some games which are not very intensive may actually go beyond 144FPS. In those cases you can limit the FPS to below 140FPS so Freesync doesn't get disabled. If your monitor is only 60Hz then Freesync will be less useful.

Freesync is very nice. It gives such a smooth experience without any tearing or stuttering ever. Just disable VSync in your game and limit the FPS to below 144 FPS if your hitting that high. Some modern games have a FPS limiter in the options, otherwise you can use RivaTuner.

As for the motherboard. Basically the differences between different chipsets is the options it supports. Some higher end chipsets support more USB ports, more SATA ports, etc... Gamer oriented chipsets will support 2 or 4 PCI-E video slots at 16x. Lower end chipsets will only have 1 or 2 at 8x. Better chipsets have more options for overclocking. So if you only have 1 video card, a couple of hard drives and just your basic 3-4 USB devices a normal cheapo chipset will do fine. There is no need to spend $300 on a motherboard to get 2 video slots at 16x if you'll never do Crossfire or SLI. Same goes for overclocking. If you don't plan on it why buy the expensive motherboard.

There is 1 argument for the better motherboards and that is better onboard audio. If you want that then go for it. I personally recommend an external USB DAC for audio and not rely on the motherboards audio. That allows you to buy a cheap motherboard but still get 10/10 audio. If the DAC lasts you through 3 motherboards that's a big savings. More expensive motherboards will also have better capacitors and reliability and windows apps.

So basically the better motherboard could net you better performance if you plan on overclocking. Otherwise it's negligible.

Faster memory will net you better performance but it's not night and day. Also the different speeds of memory are practically the same price so it's not an issue. The timings on memory can have a bigger affect then the speed of memory. It's only recently that motherboards and CPUs actually see some useful performance from faster RAM. Faster RAM is more useful for overclocking than anything.

All being said, it's the CPU and video card that will determine your gaming performance if you are not overclocking. You have the same CPU on both builds. And the 2 video cards are practically the same performance wise. Which system will give you the best performance depends on which game you are playing. Some will perform better on the AMD and others on the Intel. Don't worry about the motherboard and memory. Just get a board that has the features you want.

So overall both systems will game pretty much the exact same with differences based on the particular game. But the AMD one will give you Freesync which is a sweet bonus. Do some searches and you will quickly see that Adaptive Sync is a huge recommendation with Gaming. You would be stupid not to build a system around the RX580 unless you plan on dropping over $500 on a new G-Sync monitor.

In the first build, change the RAM to 2666mhz or higher and ditch the cooler. You are all set. If you have money left, then get another 8gb RAM and/or SSD.
In case these are prebuilds, get these specs modified.