So why are our computers doing this? (Internet connection)

We’ve two PC’s at home, one fairly new (few months old) and one quite old (486, many years old.) Both have 56K modems installed and use the same phone socket and internet provider to access the internet, though not at the same time. The newer PC rarely reaches speeds of anything over 45k and can dip to the high 30s at times. The old 486 can manage 51-52K which is enough of a difference to annoy me. I know that the connection speed has nothing to do with anything on your PC except the modem, so what could be causing the difference in access speeds?


Either one of the two modems is a hardware modem and the other is called a winmodem , or your connection times vary to when the slower computer may log on , during a less peak time.

Back when I was on dial up , my connection speed never rose above 48k and that was on a USrobotics 56k external with all the most recent drivers.


Actually there are many “software” factors that effect modem connection speed. First I assume you are using some flavor of Windoze on each machine but not the same versions. Windows 95 “out of the box” was always faster than subsequent versions. It has to do with some settings, particularly “MTU’s” accessible in the registry. You could poke around and see if they still have the “fixes” for older systems, it is possible to raise the numbers. That said, as you implied, it really is going to make some difference at those rates but may not be as much as you anticipate. You can also go a bit nuts trying to squeeze another few “k” out of one after a while.

I disagree. While I agree that Winmodems are abominatio… er… impose a subtantial burden on the CPU, that load is unlikely to strain a modern CPU. The “connection speed” is one one many fixed, preset standard speeds, that is chosen by negotiation between the local and remote modem during the handshanking phase. A Winmodem should negotiate exactly the same connect speed, even if the CPU is near full utilization. An overloaded computer won’t be able to “fill the pipe” - i.e. process, compress, and error correct the data stream as fast as the negotiated connections speed would permit, but that won’t affect the “size of the pipe” or connection speed negotiated by the modems.

In simpler terms: when a CPU is burdened, the “connection speed” [a function of of the specific protocols and settings both modems agree to use] is not affected, but “throughput” [the actual measured rate of data transfer over time] does suffer. When you’re very distracted, you might not drive as fast as conditions and traffic regulations permit [decreased throughput], but the [connection] speed limit is determined by physical and social conditions, whether you can maintain it or not.

Since essentially all modems today can handle the full v.90 spec, I think the most likely explanation is the analog circuit, not the digital side.

a) if the two computers use different phone jacks in different places in the house, the difference can be caused by loose connections in the household phone wiring, corrosion in the jack, abused phone cables, etc. Try putting them in the same room and checking what speeds they achieve on the same jack. Many phone cords, in particular, are cheap and degrade over time (and with routine abuse).

b) though todays cheap standard chips and reference designs have specs that should easily allow them to achieve the maximum speed a line is capable of, we must remember that modem connections are analog telephony, and that an analog input or output stages may have been less than optimally tuned, may have drifted slightly from the factory tuning, or may even have been cumulatively damaged (e.g by line transients, overheating, rough handling in shipping, etc.) You can test this by swapping modems, and seeing what connection speeds each achieves on the opther computer

c) EM/RF interference is very real possibility, especially for slot-based modems. The EM/RF conditions inside the case of the newer computer is very different from the inside of the older one. The two modems may also be not be equally tolerant of common-mode interference in the household wiring (phone line or power) or low line levels in the ‘last leg’ connection to your house. If the interference is external, a good conditioning UPS on the power line, or a ferrite core on the phone line (placed as close as possible to the computer end of the cable), might clear enough interference to allow a better connection speed. If it’s internal (either inside the omputer case, or in he design and construction of the card), there are few good alternatives. You could try shielding an internal modem card with thin sheet metal, mesh, or even aluminum foil, but don’t come crying to me if your homemade shield accidentally shorts something, and blows your modem or motherboard.

There is one likely digital explanation, though: many or most modems made today claim to be v92/v44 compliant, but many really aren’t. In some cases, they are really “v92/v44 ready” and getting the latest manufacturer’s driver (if/when the manufacturer cares enough to issue a fully working driver) may bring the slower, but newer modem up to snuff. It’s worth a try.

it is likely that one modem is just more sensitive to line noise than the other. switching the modems within the computers will likely switch which runs the fastest.

Both have hardware modems and both have been running one after another so the peak and off peak times my not be to blame.
There’s Win 95 on the 486 and Win XP on the newer comp. I’ve a similar computer of my own that runs Win XP and its connection rates, on another provider in another town are similar to the one the 486 machine reaches.
So I’m not sure if its hardware or software. Should I try swapping the modems around to see what happens?

Whoah, quite a few new replies snuck up on me there! I’ll try KP’s suggestions since he provided such a comprehensive list :slight_smile:


Go ahead and tweak but Quint Essence’s brilliant suggestion to swap modems will tell you if the difference is because of software or hardware, something you don’t yet know.