You wrote "I don't want my PC to take up a lot of power (energy efficency and the lowest possible wattage (minimum of 450 W))"
The size of the PSU does not set the consumption of the PC. I can fit a 450 or 1000 Watt PSU and the PC should draw about the same Watts. In fact think about this next issue.
-> Let's say your PC is about 400 Watts so you fit a 450 Watt PSU. That's like taking your car to the Indy track and driving it at 120 MPH. It won't last long.
That's why we usually fit a PSU with double the Watts needed. That way we not not have spare power but it's not stressed.
I am looking forward to building my own gaming & productivity PC, however I am having trouble with which power supply should I use for it.
Here is the list of the other components I want to put in my PC (from Newegg):
MSI B75A-G43 LGA 1155 Intel B75 HDMI SATA 6Gb/s USB 3.0 ATX Intel Motherboard with UEFI BIOS
MSI N660 Ti PE 2GD5/OC GeForce GTX 660 Ti 2GB 192-bit GDDR5 PCI Express 3.0 x16 HDCP Ready SLI Support Video Card
Intel Core i5-3570K Ivy Bridge 3.4GHz (3.8GHz Turbo) LGA 1155 77W Quad-Core Desktop Processor Intel HD Graphics 4000 BX80637I53570K
Mushkin Enhanced Silverline 12GB (3 x 4GB) 240-Pin DDR3 SDRAM DDR3 1600 (PC3 12800) Desktop Memory Model 999002
OCZ Vertex 3 VTX3-35SAT3-120G 3.5" 120GB SATA III MLC Internal Solid State Drive (SSD)
Seagate Barracuda ST3000DM001 3TB 7200 RPM 64MB Cache SATA 6.0Gb/s 3.5" Internal Hard Drive -Bare Drive
LITE-ON 12X BD-R 2X BD-RE 16X DVD+R 12X DVD-RAM 8X BD-ROM 8MB Cache SATA Blu-ray Burner with 3D Playback iHBS212-08 LightScribe Support
TP-LINK TL-WDN4800 Wireless N Dual Band Adapter IEEE 802.11a/b/g/n PCI Express x1 Up to 450Mbps Wireless Data Rates Support 64/128 bit WEP, WPA-PSK/WPA2-PSK, 802.1x
EVERCOOL HD-F117 Aluminum HDD Cooling Device
Now here are the Power Suppies:
XCLIO GREATPOWER X14S4P3 500W ATX12V SLI Certified CrossFire Ready 80 PLUS Certified Modular Active PFC Power Supply
Antec TruePower New TP-750 750W Continuous Power ATX12V V2.3 / EPS12V V2.91 SLI Certified CrossFire Ready 80 PLUS BRONZE Certified Active PFC "compatible with Core i7/Core i5" Power Supply
Which one of these Power Supplies do you guys suggest?
If neither, then here are my expectations:
I don't want my PC to take up a lot of power (energy efficency and the lowest possible wattage (minimum of 450 W))
My budget range for a power supply is $50 - $200 (< $150 will be great).
Your suggested power supply at least has to come from Newegg (if possible).
Oh yes, and here is the PC case (also from Newegg):
COOLER MASTER Storm Sniper SGC-6000-KXN1-GP Black Steel, ABS Plastic, Mesh bezel ATX Mid Tower Computer Case