By getting a cheaper PSU, I was able to upgrade to a 7870. The power supply comes with 1x6 and 1x6+2 pins, and I assume you can use the 6+2 pin as a 6 pin. What I'm curious about is if the 530W is enough. In the system requirement page, the 7870 needs minimum of 500, which I have, but I don't know how/if that takes into account TDP or what. Assuming this build is compatible, I'm gonna go and buy the last three parts I need (the PSU, GPU, and mobo).
PCPartPicker part list / Price breakdown by merchant / Benchmarks
CPU: Intel Core i3-3225 3.3GHz Dual-Core Processor ($136.99 @ Amazon)
Motherboard: ASRock B75M-DGS Micro ATX LGA1155 Motherboard ($61.97 @ Newegg)
Memory: G.Skill Ripjaws X Series 8GB (2 x 4GB) DDR3-2133 Memory ($49.99 @ Newegg)
Storage: Seagate Barracuda 1TB 3.5" 7200RPM Internal Hard Drive ($74.99 @ NCIX US)
Video Card: Sapphire Radeon HD 7870 2GB Video Card ($194.99 @ Newegg)
Case: NZXT Source 210 Elite (White) ATX Mid Tower Case ($39.99 @ Amazon)
Power Supply: Raidmax 530W ATX12V / EPS12V Power Supply ($38.92 @ Amazon)
Total: $612.84
(Prices include shipping, taxes, and discounts when available.)
(Generated by PCPartPicker 2012-11-23 17:44 EST-0500)