Building my First Computer

Barty1884

Retired Moderator
What kind of "multimedia" exactly?

That's a solid enough build overall, and if you're creating content etc (depending on the programs used), then it's a good route to go.
Would be a pretty good 1080p gaming system too, although ~3 years might be asking a bit much of a 1050TI and new titles, although easily rectified by turning down in-game settings.

Some pointers though:
The T2 seems a waste. The Wraith Spire that ships with the 2600X is good enough, and the T2 would perform about on par.
Ryzen really benefits from faster memory, so 2400MHz is definitely underwhelming. I'd suggest returning that 2400MHz kit & picking up 3000-3200MHz if at all possible.

At $105 for the board + $30 for Wifi, you could save a bit of money by moving to a board with native Wifi:
https://pcpartpicker.com/product/43BTwP/gigabyte-b450-aorus-pro-wifi-rev-10-atx-am4-motherboard-b450-aorus-pro-wifi-rev-10

The G3 is a very good PSU, but 650W is overkill for what you need here.
A CX550M from Corsair could be had for $30 after rebate, and is more than sufficient for this build.

PCPartPicker part list / Price breakdown by merchant

CPU: AMD - Ryzen 5 2600X 3.6 GHz 6-Core Processor (Purchased For $0.00)
CPU Cooler: Cooler Master - Hyper T2 54.8 CFM Sleeve Bearing CPU Cooler (Purchased For $0.00)
Thermal Compound: Arctic Silver - 5 High-Density Polysynthetic Silver 3.5 g Thermal Paste ($7.84 @ OutletPC)
Motherboard: Gigabyte - B450 AORUS PRO WIFI (rev. 1.0) ATX AM4 Motherboard ($110.78 @ OutletPC)
Memory: G.Skill - Ripjaws V Series 8 GB (2 x 4 GB) DDR4-2400 Memory (Purchased For $0.00)
Storage: Samsung - 860 Evo 500 GB 2.5" Solid State Drive ($72.99 @ Amazon)
Storage: Western Digital - Caviar Blue 1 TB 3.5" 7200RPM Internal Hard Drive ($44.85 @ OutletPC)
Video Card: MSI - GeForce GTX 1050 Ti 4 GB GAMING X 4G Video Card (Purchased For $0.00)
Case: Cooler Master - MasterBox Lite 5 ATX Mid Tower Case (Purchased For $0.00)
Power Supply: Corsair - CXM 550 W 80+ Bronze Certified Semi-Modular ATX Power Supply ($29.99 @ Newegg)
Case Fan: Cooler Master - SickleFlow (Red) 69.69 CFM 120mm Fan ($6.49 @ SuperBiiz)
Case Fan: Cooler Master - SickleFlow (Red) 69.69 CFM 120mm Fan ($6.49 @ SuperBiiz)
Case Fan: Cooler Master - SickleFlow (Red) 69.69 CFM 120mm Fan ($6.49 @ SuperBiiz)
Case Fan: Cooler Master - SickleFlow (Red) 69.69 CFM 120mm Fan ($6.49 @ SuperBiiz)
Total: $292.41
Prices include shipping, taxes, and discounts when available
Generated by PCPartPicker 2018-12-03 08:36 EST-0500

The $70 saved, plus returning the RAM would be better utilized opting for 2x4GB 3000MHz or ideally 2x8GB 3000Mhz.