Ever since installing Windows 7 SP1, I have noticed that all programs that display my network transfer rate have been exactly 4x higher than they actually are.

For example, when I download something from a high-bandwidth web site or through torrents with lots of sources, the download rate indicated is is ~5MBps (~40Mbps) even though my Internet connection has a maximum of only 1.5MBps (12Mbps). It is the same situation with the upstream bandwidth: the connection maximum is 64KBps, but I’m seeing up to 256KBps. I have tried several different programs for monitoring bandwidth throughput and they all give the same results. I also tried different times and different days, and they always show the rate as being four times too high.

My initial thought was that my ISP had increased the speeds (without my noticing), which they have done before. However, I checked my ISP’s site and they have not increased the speeds. Moreover, when I look at the speeds in the program actually doing the transfer (eg Chrome, µTorrent, etc.), the numbers are in line with the expected values at the same time that bandwidth monitoring programs are showing the high numbers.

The only significant change (and pretty much the only change at all) that has occurred to my system since the change was the installation of SP1 for Windows 7. As such, it is my belief that some sort of change exists in SP1 whereby software that accesses the bandwidth via a specific API receives (erroneously?) high numbers while others that have access to the raw data continue to receive the correct values.

I booted into Windows XP and downloaded some things via HTTP and torrent and in both cases, the numbers were as expected (like they were in Windows 7 before installing SP1). I then booted back into 7SP1 and once again, the numbers were four times higher than possible. Therefore it is definitely something in SP1 that has changed how local bandwidth is calculated/returned.

There is definitely something wonky with Windows 7 SP1’s network speed calculation.

I tried Googling this, but (for multiple reasons), have had a difficult time finding anything relevant.

Has anybody else noticed this behavior? Does anybody know of any bugs or changes in SP1 that could account for it?