Just to clarify things, frying PC ports should not be an issue, due to ocervurrent protection implemented in most modern OS'es, be it any linux, windows,mac or whatever. Normal outcome would be N900 charging @ max 500 mA from USB port, or 1A from 2 ports using Y-cable. Worst case scenario should be temporaly disabling on-topic USB port by OS, shouting @ user that peripherial device exceed current limitation drain.
Of course all of this is unless there is some bug in overcurrent protection, that I'm not aware of (which got high chances to be the case), so use at Your own risk.
Thanks for the info... Fortunately, i got one with smart protection - otherwise i would screw it many years ago, when tried to check max port current with multimeter A measurement (which obviously made overcurrent prot. to go berseker - don't ask, it was one of most stupid ideas i had during my hardware modifications learning phase...). Fortunately, Os just shouted at me to get out with that, and disabled port until driver restart. Really good to know that there are fuse-based solutions still circulating...
By the way, out of curiosity - why everything else connected to that 700 mA port "dims"? Shouldn't peripheral things drain only as much as they need from port current "pool", so they don't care if port can provide 700 mA or 7A?
The charger chip in N900 happily operates at, for example, 4.5V input. The Hub's powersupply was unable to provide sufficient current, so voltage sagged to below 5V.
