Read this first.http://en.wikipedia.org/wiki/PCI_Express
It says that-PCIe 2.0 motherboard slots are fully backward compatible with PCIe v1.x cards. PCIe 2.0 cards are also generally backward compatible with PCIe 1.x motherboards, using the available bandwidth of PCI Express 1.1. Overall, graphic cards or motherboards designed for v2.0 will work with the other being v1.1 or v1.0a.
If it helps,I am running an HD 6850 PCI-E v2.1(on the box) on an MSI MS 7525 without any problems.However,my processor(Core2Duo E7400) does bottleneck my card.
Also,that PSU is a good one.