More cores only equals more performance if you're encoding a video.
That's it.
Their "cheaper" CPUs require more expensive motherboards, as well as more expensive cooling options and more expensive PSUs.
GHZ don't mean anything.
This intel build will perform the same, but for 200 less:
http://www.3dmark.com/compare/fs/4608302/fs/4765370 (this is an 8350 @ 5ghz vs an i5-4460 at stock.)
PCPartPicker part list /
Price breakdown by merchant
CPU: Intel Core i5-4460 3.2GHz Quad-Core Processor ($163.99 @ SuperBiiz)
Motherboard: ASRock H97M PRO4 Micro ATX LGA1150 Motherboard ($71.98 @ Newegg)
Memory: Crucial Ballistix Sport XT 8GB (2 x 4GB) DDR3-1600 Memory ($34.99 @ Newegg)
Storage: Kingston SSDNow V300 Series 240GB 2.5" Solid State Drive ($71.10 @ SuperBiiz)
Storage: Kingston SSDNow V300 Series 240GB 2.5" Solid State Drive ($71.10 @ SuperBiiz)
Video Card: EVGA GeForce GTX 970 4GB Video Card ($319.99 @ SuperBiiz)
Case: NZXT S340 (Black) ATX Mid Tower Case ($59.99 @ Micro Center)
Power Supply: EVGA 400W ATX Power Supply ($27.00 @ SuperBiiz)
Monitor: Asus VS248H-P 24.0" Monitor ($142.99 @ NCIX US)
Total: $963.13
Prices include shipping, taxes, and discounts when available
Generated by PCPartPicker 2015-11-01 05:10 EST-0500
I'm not being an Intel fanboy, Intel is just hands down better, it's the smarter decision, this is just an example, and not what I think you should actually get.
And like Siz said, you're not gonna reach that OC you want with that PSU and Mobo, you'll need to drop around $150-200 on each if you want to OC that high.