Have I made a huge mistake buying Dell Inspiron 5558, i7, 16gb Ram, Eight months back, Its my first dell purchase.

From the First day First boot machine heats up and shutdown, that time sales person and dell customer support tell me not to worry thermal pest will settle gradually after that machine will be normal.

After that -

1) dell change my heat sink - not resolved.

2) change mother board, update Bios (A11), still problem are not solved,

I haven't even used for 30 min and its heating up; CPU thermister temp. reached up to 93 degree high and low is 67 to 69.

I have windows 8.1 on this machine and it feels so slow on this new machine.

I am fade-up with this machine, infrequently  shutdown due to this wants to rework again and again and again !!!!!

There is any solution ?