Get a quality supply, at least 80 PLUS Bronze (Gold is preferred) from a quality maker. Your B450 Gigabyte DS3H motherboard shows DDR4 3200 as the RAM speed limit on PCPP and you have the opportunity to get that 1660 Super by simply going DDR4 3200 RAM vs the DDR4 3600 RAM. A GTX 1660 Super for 225 and the DDR4 3200 16 CAS 2x8GB RAM for 65. And last but certainly not least, don't cut corners on the budget with a cheap power supply. A GTX 1660 for 205 and the DDR4 3600 16 CAS 2x8GB RAM for 85.
And remember, the slowest SSD can run circles around the fastest hard drive. If the budget is a factor, I sure would not hesitate to go for a less expensive motherboard in favor of more RAM (at least 8GB, preferably 2 x 8GB for 16GB total), a better graphics solution, and certainly a SSD over a hard drive.
Along with the release of the unlocked i5-8600K, this is the first time that six-core processors have featured in the i5 line-up. Intel B365 Ultra Durable motherboard with GIGABYTE 8118 Gaming LAN, PCIe Gen3 x4 M.2, 7 colors RGB LED strips support, Anti-Sulfur Resistor, Smart Fan 5, DualBIOS, CEC 2019 ready Supports 9th and 8th Gen Intel Core Processors Dual Channel Non-ECC Unbuffered DDR4 New Hybrid Digital PWM Design High Quality Audio Capacitors and Audio Noise Guard with LED Trace Path Lighting Ultra-Fast M.2. The type and amount of RAM, graphics solution, and drive access (SSD vs HD, for example) all factor in. The i5-8400 is a competitively priced hex-core processor from Intel’s 8th generation of Core processors (Coffee Lake). Corsair Vengeance LPX DDR4 3000 C15 2x8GB 74: SanDisk Extreme 32GB 28: Seagate Barracuda 2TB. Cooler: Noctua NH-D15S w/ white chromax bling. Motherboard: Asus ROG Strix X570-E Gaming. RAM tests include: single/multi core bandwidth and latency. GPU: Gigabyte 980ti Xtreme (also placeholder), deshroud w/ generic 1200rpm 120mm fans x2, stock bios 130 power, no voltage offset: +70 core +400 mem. Take your pick! I note while the motherboard's performance certainly plays a role in overall computer performance, it is but one factor in the equation. Gigabyte B360M DS3H (2,283) Gigabyte Z370P D3 (1,979) Asus PRIME Z370-P (1,799) Asus PRIME B360M-A (1,794).