Temp could play a part in this, but it can also just be a change in your use pattern, and that extends all the way to what website you visit.
If if sleeps, not so big an issue, it should drop power draw down to 5-10watts, your screens at idle can actually use use more than the pc while sleeping. If you simply let it go idle and sleep the screens it can still idle at 80 watts or even more depending on what's in the system and how it's tuned. While not perfect by any means, but a simple equation is that 1watt running 24hours a day 365 days a year will cost $1 per year, so you can kind of figure your cost based on that but you will still need to know how many watts it's using at idle and sleep either by a Kill-a-watt, UPS with monitor or just research the parts themselves. Again, your screens are soaking more than you'd expect though (as can your audio).
The other issue is Windows.
It NEEDS a reboot once in a while, if you're a completely casual user, no gpu, just some browsing and Office, once a week is probably fine, but the fact that you're using so many screens tells me that's likely not the case. And if you browse Reddit, oh boy... No, their website is a sh$t show and will decimate your system*. I've never (even without Reddit) really been able to get more than a few days without a reboot to clear out the memory before I could tell something was not running as it should. I've seen people go months without and not see issues, but I could, the systems always run like garbage. Reboots are the biggest system tuning tool Windows has and I recommend people do it at least once a week at the longest, not the shortest.
*Reddit's front page and sections, how do I explain this... Each item shown is not just the item in the first post for each page, it loads the entire page and comments for each entry and auto loads/starts all videos and gifs. So as you scroll you're effectively loading more and more full pages and comments. Each video entry you see on the front page is like loading a page on Youtube, including comments. And the poor programming doesn't stop there, it acts like it's creating a memory leak, possibly Java and possibly related to the compression algorithm they use to allow endless scroll (which needs to die!) and once it starts to drag down the system even closing the browser and reopening will not fully purge the cache of what it loaded and system speed will suffer as a result. Sometimes, if you catch it early enough it can revert some of it, but once you really see lag, odds are the only real fix is a system restart. Note this mostly applies to the desktop version in Chrome and Firefox, with only Mac being mostly exempt hence my suspicion about the cause. Other OS seem to deal with it better, as does Safari. Honestly, considering what it's doing, it's amazing it works as well as is does and the devs deserve respect for that, but whoever put them in this spot that this was the best solution needs to be fired for the decision.
