I'm not familiar with Intel and so don't know what to expect of a 7700 temp-wise but that's not an overclockable board or cpu so common sense says you shouldn't be having temp problems unless using the totally inadequate stock coolers Intel bundles in some CPU's. And maybe even then only if it's fouled with dust.
Also check your case fans for proper functioning: there should be one or two in front blowing in, and one or two in back and top blowing out.
An Intel expert might have more for you to check out.
80c. under 100% usage is ok.
The processor will monitor it's temperature and will slow down or shut off if it detects a dangerous temperature.
That is around 100c.
What is your temperature at idle with nothing going on?
I expect to see something like 10-15c. over ambient if your cooler is working properly.
If you are using the stock intel cooler, verify that it is securely fastened with all 4 pushpins through the motherboard and locked.
What is the make/model of your case?
What fans do you have as front intakes?
Any cooler needs a good supply of fresh air to let it do it's job.
80c is undesirable, but also acceptable, I could say its the borderline between safe and pushing it, ideally you should be aiming to a max of 75C, but 80C for short periods is not something you should go crazy about, yet, if you can, and i'm guessing you're using stock cooler because any decent aftermarket can keep 100% under 80c on my experience at stock values, and considering you're using a non overclockable 7700, extra true...
another easy option would be to undervolt the cpu, something often very easily doable on stock settings to keep things cool but, i dont think your motherboard allows for it even if you had an unlocked processor, someone correct me if im wrong.
I think if your CPU is running at a temp of 80C you don't need to be too concerned. As long as it's doing something. (if it's idling at 80C, or web-browsing, come back to us). I've just checked the intel specifications of the i7-7700 and (as with all intel CPUs, I believe) they state that it will be stable up to 100C, before it will begin to fail. Intel call this the 'T-Junction'.
Intel CPUs are fairly robust - I've used them my whole life (with either the stock cooler, or a cheap aftermarket cooler) and never had one fail on me. Here's a link to the product page for your CPU. i7-7700 details. Scroll down to where it says T-Junction to see for yourself, and feel free to google about it intel T-Junction for more peace of mind.
Let us know if you have any other questions on this.