Download Speed fluctuating when using ethernet cable

[father stretch my asshole]

Hi guys,
so I am kinda sure what my problem is but I want to ask if anyone knows a solution. I have a rather fast internet connection. When I download games my speed goes up and then constantly drops down to 0 mb/s. It then starts bouncing back and forth between downloading and then going back to 0mb/s. I am pretty sure this has to do with my HDD, because when I download games to my SSD my speed shoots up and simply stays there. I have the Seagate BarraCuda 2TB (ST2000DM008). Now I am wondering, is there a way to restrict how much steam uses my HDD to kinda find a "sweet spot" in the balance of download speed and disk usage, or do I need to get a faster HDD or just swap it out for an SSD?

Thanks

[Cathulhu]

Steam processes data as fast as your system can do. So if your HDD cannot cope with processing data, then get something faster, like an SSD.
Downloaded data is encrypted and compressed.

[Supafly]

Open Task manager and look at what CPU and Drive usage is at. If one or both near/at 100% they are too busy decompressing and installing the last complete chunk to continue downloading.

[The_Liquidator]

I have almost the same problem, only i install directly on my SSD, CPU Usage is 10% Ethernet is a mess. Goes from 60 kbps to 0, and to 120 kbps to 0 all the time
I have fiberglas 1GG up and Down connection, And this happens to every game i download. So there must be something wrong

[Iceira]

Old game can also do this, many forget this, the lesser a game is DL then it will be seen as in-frequent access and can be seen as worse to fetch,

server use this already cant see why steam will not do same. ( pretty sure file size can also effect this not sure then a game can be seen as small 10year old games might have reduce main steam DL, test this yourself or explan better, i bet even they other here, might have seen this, but we forget about it. and only thinking on highend game.