So its only a week old. If you go their they have to exchange it if you are unhappy with it. As long as it looks new without damage.
The benchmarks between the two SSD's show significant speed differences. However it is said that users wont notice a difference when using it in day to day use, unless transferring files from a setup also capable of those speeds (so only some sort of thunderbolt SSD or thunderbolt RAID setup)
I guess if you get a new one with the toshiba. Return it for a full refund, say the computer doesn't fit your needs like you thought it will. Then purchase another one, haha. Jus kiddin. I personally wouldn't worry about the SSD difference too much.
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I took a screen grab but the faint dark tinged thin line doesn't appear on the screen grab. Hmm strange
Well thats because a screen grab is an image of what the GPU is sending out, not of what is on the screen. If the screen for example is smashed and you take a screen grap and look at it on another computer, it will look perfect.
If your problem would show up on a screen grab it would mean that you have a GPU problem.
You need to take an actual photo of it.