Issue: When doing a speed test - download often jumps all over the place and hits up to 330mbps.. then settles at anywhere 10mbps to 74mbps. Upload gradually increases up to slightly over 5mbps.
Speed test sites used:
speedtest.net speakeasy.net timewarner.com
Steps taken: Time Warner initially were called in due to bad upload speeds (0.14mbps) which after a load of hassle and infuriating communications was found to be a bad node their end which was affected by noise (over a month to work that out).
New cables have been dropped from the pole to the house, new cable run from the junction box to the outlet.. tests from the pole show good signal - using their handheld device showed good signal too from the modem.
Multiple computers here (running Windows 7 - specs below) have been used (including a TWC engineers laptop). All tests show the aforementioned problem - except the engineers laptop (running XP) when he used the TWC site.. which gave the correct behaviour and results.
He then tried speedtest and speakeasy test sites and experienced the same issue as before.
The download graph on speedtest.net often shows a sawtooth pattern - peaking at the 300+mbps then hitting either 0mbps or slightly above.. possibly causing occasional buffering issues on streamed videos. It is not (normally) a smooth and maintained increase.
Several modems have been used - initially the Motorola SBG6580, then several Arris models followed by another Motorola yesterday.
All engineers have been stumped by this - does anyone have any suggestions?
Main System Specs:
i7 3930K CPU 16GB RAM ASUS Rampage Extreme IV MOBO Using Wired Connection
If any other details would help - please let me know.. apologies for the long post and any crucial omissions/oversights.