no, you can't do that either. loweing the connection slower than the correct speed will also cause problems. you need to set the connection speed to exactly 80% of the connection. just make sure you don't get confused with Kbps and kBps.
1 kBps = 8Kbps
check your router settings by invoking the router's Internet Protocol. the usualy IP address for a router is 192.168.0.1. However, sometimes they differ. to find out your router's IP, right click > properties on your interenet adaptor (whether it's wireless or an ethernet based wired adaptor), you should find this through your network connections folder.
in the properties windows of your adapter, you shoud also see a “details” tab. that will show you your “default Gateway” (your router), sometimes also known as your DHCP (Dynamic Host Configuration Protocol) Server. the address shown after these two will more than likely be the same and is the adress for your router. enter this number into a web browser.you will be prompted for a username and password. the usual default is Admin / password. but if you've changed it, only you will know.
Once into your router, find the status of your connection. every router is different, but the main page should tell your connection speed in either Kbps or kBps, or often enough kbps.
you can easily tell whether it's Kbps or kBps though because Kbps is 8 times that of kBps. so if you have a rather large number like this one: 2272, or 8000 or 12100, then it's telling you the connection speed in Kbps. if however, the numbers you see look a lot smaller, like: 284, or 1000, or 1512, then chances are it's telling you the connection in kBps.
now to find 80% of your connection you need to do a simple formula:
[your connection speed] / 8 * 0.8 =
using my connection speed from my own router, i can show you an example:
2272kBps divided by 8 = 284Kbps. 284 x 0.8 = 227.2Kbps (227Kbps is the exact same speed my actual download speed is).
try it yourself and then input the maximum global download and upload speeds into your torrent client. if your calculations are correct, you should be able to download, and still use the internet with minimal slow-down.
however, if the setting are incorrect, the problem is likely to continue.
a case example is a customer i had the other day. he could not use his internet connection at all. i took in his laptop and very quickly realised that he has set up utorrent to start when windows starts, and to then start downloading. he had not set up the connection speed properly and it was flooding his connection. it took a couple tries to figure out his proper connection speed and enter the correct settings, but when I did, both the torrent client and the web browser worked together with almost no slow down.