RAM and SSD draw/use minimal amps/watts from the power supply, approx. 2W to 3W for each stick of DDR3 RAM at 1.5V, and approx. 0.6W to 2.8W for each Solid State Drive (http://www.buildcomputers.net/power-consumption-of-pc-components.html)
On your current setup:
Your i5-4440 is an 84W-TDP CPU (https://ark.intel.com/products/75038/Intel-Core-i5-4440-Processor-6M-Cache-up-to-3_30-GHz) that actually draws less than that, about 55W-65W on the average (http://hexus.net/tech/reviews/cpu/66525-intel-core-i5-4440-22nm-haswell/?page=8).
Your GTX 1070 is a 170W-rated GPU (https://www.evga.com/products/product.aspx?pn=08G-P4-5173-KR) that can actually draw in the vicinity of 180W at full stressed loads (http://www.guru3d.com/articles-pages/evga-geforce-gtx-1070-sc-superclocked-gaming-review,8.html).
Your other components, HDD (~9W), RAM (~3W), motherboard and appurtenances (less than ~50W) would draw less than ~60W.
Overall, in my theoretical estimates, you will rarely get past 300W consumption from your PSU.
The Corsair CS550M PSU is rated at 550W but actually only outputs at a rated wattage of 516W at the 12V rail (i.e., 43A). Though when fully stressed (not recommended), theoretically speaking, your PSU can reach its peak power of 605W (http://www.corsair.com/~/media/corsair/download-files/manuals/corsair-psu-spec-table.pdf).
Efficiency-wise, since your CS550M offers 516W at 12V, you want to hit the vicinity of 40% to 60% of its rated power draw (i.e., 206.4W to 309.6W) to get the best efficiency ratio. Going less or beyond that range, the efficiency goes lower (where the increase in power drawn from your wall socket only gets converted to heat).
CS550M efficiency curve based on system load:
The CPU and the GPU are the most power-consuming components of a rig. Adding some low-power consuming devices such as RAM sticks, SSDs, fans, and LED lighting would have minimal effect on the power draw.
As to which other CPU and GPU you can upgrade to, depends on your needs.
Again, basing on your current specs, there is a high probability that in certain AAA games in lower resolutions, your current i5-4440 would be hindering the performance of your powerful GTX 1070 GPU. Given that you have a Haswell H81-chipset motherboard, you can upgrade the CPU to an i7-4790 (provided, a BIOS update on the motherboard to work with Haswell-Refresh CPUs such as the i7-4790 for it to work).
The i7-4790 is a non-OCable CPU (which pairs with your non-OCable H81 mobo) that has an 84W-TDP rating also (http://ark.intel.com/products/80806/Intel-Core-i7-4790-Processor-8M-Cache-up-to-4_00-GHz). Actual power consumption of the i7-4790 would be slightly higher than the 4-core/4-thread i5-4440, due to hyperthreading (4-core/8-thread) and faster clock speeds (http://www.guru3d.com/articles-pages/core-i7-4790-processor-review,11.html), but still less than 84W.
Your GTX 1070 is ideal for 1440p/60Hz monitors or 1080p/~120Hz monitors. The i7-4790 and your 550W-PSU can handle a GPU upgrade to a GTX 1080 (meant for 1440p/~120Hz or 1080p/144Hz+ monitors), which is only a 180W-TDP GPU (https://www.techpowerup.com/gpudb/2839/geforce-gtx-1080).
As mentioned, you want to hit 40% - 60% of your PSU's supply curve for better efficiency. Upgrading to more powerful components would lessen its efficiency, but still would have more than enough juice to be able to run it.