I applied thermal paste on the CPU with the initial bored but scraped it off during the time I waited for the replacement board
Did you clean it off properly and then re-apply a fresh amount - the CPU will overheat otherwise and when it does the MBs thermal sensor will shut the system down to avoid frying the CPU, this takes a matter of seconds to occur.
Please provide further information regarding the following so that we can check compatibility**
See below; and the required PSU output;
Corsair Vengeance 2x4GB - please provide a link to the specific Ram.
Crucial 2x2GD - same as above please.
What type/spec and how many HDD/s do you have.
What type of and how many optical drive/s do you have.**
For the best and most stable performance you should where possible purchase a CPU and Ram that have been tested and approved by the motherboard manufacturer, this is referred to as the QVL ( qualified vendors list ) understand though that there are too many products released for them all to be tested so other hardware will be compatible but not proven to be.
When browsing other forums some people suggested a new power supply,
To avoid any confusion or conflicting advice it is recommended that you only work with one forum, are you receiving assistance on any other forum.