What effects does underclocking do?

[xPASTELx]

Ik overclocking does wonders getting extra juice but how bout under clocking?

[fapar]

Ik overclocking does wonders getting extra juice but how bout under clocking?

Specify what you mean. If the down voltage for the card 470/480/570/580 you need to use WattTool-0.92 or newer OverdriveNTool.
You also need to change the memory timings.

[dadesu]

Underclocking is for must in mining mode, especialy in big mines.
With underclocking you can control power consumption and heat dissipation.
Every pro miner must use underclocked cards because of that.

[leowonderful]

Underclocking and undervolting together with memory timing changes results in lower power consumption and similar hashrates. Underclocking by itself isn't as effective by itself. Many people have guides about undervolting and underclocking on this part of the forums for reference and you can also tinker around with your GPUs to find their sweet spots. It can vary even by card brand.

[moonmaths]

apropos eli5 shit, does anyone know some good introductory videos explaining on a more granular level how gpu's function, especially if they're in relation to mining? 
I think everyone gets that the name of the game is the most hashes for the least amount of energy spent.

[Agozyen]

Underclocking is for must in mining mode, especialy in big mines.
With underclocking you can control power consumption and heat dissipation.
Every pro miner must use underclocked cards because of that.

A fringe benefit of lower power consumption and lower heat is that the cards will last longer and you will experience fewer technical issues that are related to heat.  Your overall cooling costs are reduced as well.

[ivakar]

Ik overclocking does wonders getting extra juice but how bout under clocking?

Underclocking will allow you to squeeze better performance per watt ratio.
Take for example performance of gtx1080ti in equihash - @ 90-95 pl card pushes 760sols per 2.8 sol / W
@ 80-85pl card pushes 720-730 sols  it is 3.1 -3.2 sol/w. and @ 65-70 pl card pushes 640-650 sols and it is 4 sol/w
The choice is yours

[minerlai]

usually when you increase the clock and mem together the card throws a fit. By under clocking and increasing the memory clock, it allows you to mine a memory hard coin like ethereum.