nope it doesn't help you in any way, unless your games are over a few gigabytes big.
boot speed doesn't matter -> my laptop starts in 4-5sec win10, but that's because i have uefi boot with shitload of services and what not. and it has evo 840 (2.5" drive)
real performance matters in 4K random read which is around 40MB/s and that is super good, because HDDs are around 0,15MB/s -> which makes them really slow when loading windows because of lot of fragmentation and small files.
now about games -> let's say you're doing an android game, limit 100mb. let's say you have 100mb, 1000 files, which is 0.1mb per file. that's 4K reading -> 2.5s if you have a ssd with slower 4K it will go even worse.
if you have a huge game ~500-1000mb with big files ~ ssd uses seq. read which is in my case ~460MB, let's say i have 2 big files of 450MB and 100MB of small files = 2 sec + 2.5sec = 4.5 sec if you have a drive with faster seq (PCIeSSD) let's say 900MB/s it will be 1 sec + 2.5sec = 3.5s , so yeah, nice gain of 1 sec! for probably double the money.
as you can see here:
in real bench ("Work") - > the gain is so subtle from PCIEssd that it doesn't really matter -> check the first table to see what kind of files are there.
in copying big files ("Media") -> you do gain some significant speed.
anyway in any case - if you want to save your money - buy samsung evo 850, cheap, good, fastest 2.5" ssd probably today. if you really want that "little" upgrade in terms of PCIeSSD and visually no speed difference - buy the PCIe version of samsung 850.
in any way if you're coming from a HDD you will notice huge huge difference so it won't matter what you buy because you'll be blown away
anyway can you post your current PC specs arima?