I've started to look around and research components for building myself a Tower PC (I've already purchased the motherboard and Tower case) and have come across something I'm not sure about regarding PCIe version compatibility across the CPU, GPU, and Motherboard. Hopefully someone can help me with this 
The motherboard I have purchased is an MSI Z77A-G43 (PCIe 3.0)
http://uk.msi.com/product/mb/Z77A-G43.html
The Graphics card I'm looking to purchase is a MSI Nvidia Geforce GT640 (PCIe 3.0)
http://www.msi.com/product/vga/N640GT-MD2GD3-OC.html#?div=Overview
The CPU I'm looking to purchase is an Intel Core i3 3220 (PCIe 2.0)
http://ark.intel.com/products/65693/Intel-Core-i3-3220-Processor-(3M-Cache-3_30-GHz)
I am on a low budget so I cannot afford a CPU that's PCIe 3.0 compatible
What I'm wondering is, will these components work fine together? Will the Graphics card just run at PCIe 2.0 instead of 3.0 as the CPU does not support 3.0, or will I NEED a CPU that is PCIe 3.0 for the system to work at all?
If these components will work fine together as they are then I know that I can just upgrade the CPU at a later date to take advantage of PCIe 3.0.
Any advice on this will be greatly appreciated

The motherboard I have purchased is an MSI Z77A-G43 (PCIe 3.0)
http://uk.msi.com/product/mb/Z77A-G43.html
The Graphics card I'm looking to purchase is a MSI Nvidia Geforce GT640 (PCIe 3.0)
http://www.msi.com/product/vga/N640GT-MD2GD3-OC.html#?div=Overview
The CPU I'm looking to purchase is an Intel Core i3 3220 (PCIe 2.0)
http://ark.intel.com/products/65693/Intel-Core-i3-3220-Processor-(3M-Cache-3_30-GHz)
I am on a low budget so I cannot afford a CPU that's PCIe 3.0 compatible
What I'm wondering is, will these components work fine together? Will the Graphics card just run at PCIe 2.0 instead of 3.0 as the CPU does not support 3.0, or will I NEED a CPU that is PCIe 3.0 for the system to work at all?
If these components will work fine together as they are then I know that I can just upgrade the CPU at a later date to take advantage of PCIe 3.0.
Any advice on this will be greatly appreciated

