I have the same components except for GPU for the past 9 months.
For CPU - Use Cinebench R23 and compare your score online (youtube and/or other review sites).
(There are 2 modes for this CPU - PL1 and PL2. PL1 will make the CPU max at 4GHz all core and 65W max power consumption. PL2 will use the full potential of the CPU with increased power consumption. Depending on the cooler you use the temperature and power consumption will vary. With the stock cooler, the CPU will hit 90+°C on PL2). If Asus Power Enhancement feature in BIOS is ON it is PL2, if it is off, it is PL1. Motherboard defaults to PL2 iirc.)
For RAM - 2400Mhz is the base spec for that RAM. Make sure XMP is enabled in BIOS. Log in and check with CPU-Z memory and SPD tabs and check whether the specs are correct. Run memtest86 for minimum 1 hr (only this test should be running) and check for any errors.
For GPU - Use GPU-Z and see the specs are correct. Install the latest drivers and use Unigine Superposition benchmark to stress test the GPU. You can run the benchmark repeatedly as much as you want to load the GPU continuously (Loop test is available in pro version). Another tool is Unigine Heaven Benchmark which is completely free has loop feature)
For SSD - Use Crystal disk info to check the specs and HDTune/Harddisk sentinel/Crystal Disk Mark to test speeds and compare it online with a product review website's result.
If system boots up motherboard is good. If you want to be super careful, you will want to check all ports, headers, PCI slots, RAM slots, etc., it's upto you.
Use HWINFO64 during all test and notice the power consumption and temperature for the component under test.