is there any compatibility issues in this system

Solution
Well, pc part picker mentions all of the compatibility issues for you - thats the point.

Here they are in case you missed it:
MSI 970 GAMING ATX AM3+ Motherboard has an onboard USB 3.0 header, but the BitFenix Merc Beta (Black) ATX Mid Tower Case does not have front panel USB 3.0 ports.
Some AMD 970 chipset motherboards may need a BIOS update prior to using Vishera CPUs.
The BitFenix Merc Beta (Black) ATX Mid Tower Case supports video cards up to 320mm long, but video cards over 270mm may block drive bays. Since the Gigabyte Radeon R9 270X 2GB WINDFORCE Video Card is 297mm long, some drive bays may not be usable.

Tbh really, I have never found an issue with 970 boards + 6300 cpus and I don't think the BIOS updated is a must...
Well, pc part picker mentions all of the compatibility issues for you - thats the point.

Here they are in case you missed it:
MSI 970 GAMING ATX AM3+ Motherboard has an onboard USB 3.0 header, but the BitFenix Merc Beta (Black) ATX Mid Tower Case does not have front panel USB 3.0 ports.
Some AMD 970 chipset motherboards may need a BIOS update prior to using Vishera CPUs.
The BitFenix Merc Beta (Black) ATX Mid Tower Case supports video cards up to 320mm long, but video cards over 270mm may block drive bays. Since the Gigabyte Radeon R9 270X 2GB WINDFORCE Video Card is 297mm long, some drive bays may not be usable.

Tbh really, I have never found an issue with 970 boards + 6300 cpus and I don't think the BIOS updated is a must. Sure, it may help stability and performance but it won't stop you from booting and getting the system running in my experience.
 
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