Hi, guy i got a old sony vaio desktop, i was wondering if i can put EVGA 01G-P3-1556-KR GeForce GTX 550 Ti (Fermi) FPB 1GB 192-bit GDDR5 PCI Express 2.0 card in. i dont know what kind of motherboard it came with, but the model of the desktop is VGC-RB34G
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.
I advise you to keep this thread open for some time. Other members may advise you to change your processor as well.I don't know much about bottlenecking,but my GPU does get bottlenecked by my processor.I only said what I myself have done ie I was also going for an EVGA GTX 550 ti but instead,went for a Sapphire HD 6850. Keep this thread open for some time.