Mahmud Reza Utsas

This is one of the original Haswell skus, and not the refresh, so it should run on your board without necessitating a BIOS update.

Does the Gigabyte website list it as compatible?

It will work fine. 

http://www.cpu-upgrade.com/mb-Gigabyte/GA-H81M-S2PV(rev._1.0).html
 
I found this for you - it seems like it does indeed support the i5 4570.
 
Feel free to check the list yourself

I don't think a 1050 will bottleneck with a g4400?

It will run without a problem. The extra 6-pin connector is for more power in case you want to overclock.  

Even though it doesn't have a 6-pin connector, the PSU will still struggle to keep up with the entire system as the GPU still draws power from the motherboard. You can use the GTX 1050 Ti with this PSU, but make sure you don't overclock until you get a higher quality PSU.  

no. get rid of that PSU as soon as possible. the change of it blowing up when under load is very high

Oh ok, so you had an R7 370 but now you wanna upgrade? Then yes, the GTX 1050 Ti would work without a doubt.  

100% 1050ti

i just ran a test with hdtune and it says transfer rate is 
minmum   42.2MB
max          114.6MB
avg           100MB
burst          22.4MB
cpu usage   %13.7

okay, you are trying to write data into it
 
unfortunately even with USB3 support, writing down flash drive isn't fast as it read.
it just nature of flash drive.
 
41MB first load, is the speed of your data buffering into system before it got passed to your flash drive.
try to copy from your flash drive to your ssd/hdd.
 
btw how speed write on your ext. hdd?

not sure the exact model but heres the link where i bought it
http://www.newegg.com/Product/Product.aspx?Item=N82E16820171923&nm_mc=KNC-GoogleAdwords-PC&cm_mmc=KNC-GoogleAdwords-PC-_-pla-_-USB+Flash+Drives-_-N82E16820171923&gclid=CNOGnM2F3ccCFZKIaQodcCgDSw&gclsrc=aw.ds
 
any help is much appreciated

yes i also have a toshiba 3.0 2TB external drive plugged in , but its plugged into one of my back usb 3.0 ports