Corsair CC-9011048-WW Carbide Series Air 540 Windowed ATX High Airflow Cube Performance Computer Case with White LED Fan - Arctic White


Intel Core i7 i7-4790K CPU (Quad Core 4GHz, Socket H3 LGA-1150
 


Asus Nvidia GeForce GTX 970 Strix Graphics Card (4GB, GDDR5, PCI Express 3.0



HyperX FURY Series 16GB (2x 8GB) DDR3 1866MHz CL10 DIMM Memory Module Kit - Black 



Asus H97-PRO GAMER Intel 1150/Intel H97 ATX Motherboard



Corsair CP-9020056-UK RM Series RM850 80 Plus Gold 850W ATX/EPS Fully Modular Power Supply Unit（选这个电源是因为打折，和和650基本一个价钱）

Samsung 2.5-Inch 250 GB 850 EVO Solid State Drive 

Seagate Barracuda 3.5 inch 2TB 7200 RPM 64MB 6GB/S Internal SATA Drive

TP-Link TL-WN951N 300 Mbps Wireless N PCI Adapter

Cooler Master Hyper 212 EVO (120mm)

请各位大神帮帮参谋一下，稍微超了一些预算，哪里还能在减减？如果这样比较好，那么就这样也行。还有就是
Arctic Cooling MX-4 4g Thermal Compound，我需要买这个吗？最后就是操作系统了？是不是从网上下？现在用的是WIN7，需要买WIN8吗？从网上买是不是需要买正版的？还是就是随便在国内的网站下个盗版的？非常感谢一代淫僧，允魂，googscn等的帮助。