what do you think of my nas build?

Not sure what you mean by 'nas', not sure why you have a $90 motherboard with this, and not sure why you have a 4tb HDD with no video card.

PCPartPicker part list / Price breakdown by merchant

Type Item Price
CPU Intel Core i5-4440 3.1GHz Quad-Core Processor $163.95 @ SuperBiiz
Motherboard Biostar B85MG Micro ATX LGA1150 Motherboard $51.74 @ Mwave
Memory Crucial Ballistix Sport 8GB (2 x 4GB) DDR3-1600 Memory $52.99 @ Newegg
Storage Western Digital Caviar Blue 1TB 3.5" 7200RPM Internal Hard Drive $52.49 @ OutletPC
Video Card XFX Radeon R9 280X 3GB Double Dissipation Video Card $228.99 @ SuperBiiz
Case Corsair 200R ATX Mid Tower Case $56.99 @ NCIX US
Power Supply Corsair Builder 430W 80+ Bronze Certified ATX Power Supply $34.99 @ Micro Center
Prices include shipping, taxes, rebates, and discounts
Total (before mail-in rebates) $662.14
Mail-in rebates -$20.00
Total $642.14
Generated by PCPartPicker 2015-04-28 22:48 EDT-0400

If you can go over.

PCPartPicker part list / Price breakdown by merchant

Type Item Price
CPU Intel Pentium G3258 3.2GHz Dual-Core Processor $64.98 @ NCIX US
Motherboard ASRock H81M-ITX Mini ITX LGA1150 Motherboard $58.99 @ SuperBiiz
Memory G.Skill Ripjaws Series 8GB (2 x 4GB) DDR3-1333 Memory $50.99 @ Newegg
Storage Western Digital Caviar Blue 1TB 3.5" 7200RPM Internal Hard Drive $52.49 @ OutletPC
Video Card Sapphire Radeon R9 280 3GB Dual-X Video Card $167.99 @ Newegg
Case Thermaltake VL80001W2Z ATX Mid Tower Case $22.99 @ Micro Center
Power Supply Corsair RM 450W 80+ Gold Certified Fully-Modular ATX Power Supply $84.99 @ Micro Center
Optical Drive Samsung SH-224DB/RSBS DVD/CD Writer $13.99 @ Amazon
Prices include shipping, taxes, rebates, and discounts
Total (before mail-in rebates) $572.41
Mail-in rebates -$55.00
Total $517.41
Generated by PCPartPicker 2015-04-28 22:50 EDT-0400

If you can't. Both are great, this one is probably better for your price range.

/r/pcmasterrace Thread Link - pcpartpicker.com