|"I've tried plugging it into all the available ports, but it still doesn't have any speed up."|
See the referenced link in response 1 to nail down which USB ports are the best ones to use. Also, if you plug it into a hub of the type I mention, it MAY work fine when plugged in by itself into such a hub, but it may NOT when something else is plugged into the same hub.
If the subject external drive's speed is compared when it is plugged into the same USB port that is one in which it works properly in the different operating systems, then there must something else that is different.
- whatever operating system you load, you must load the driver files for and/or information about the mboard's hardware (main chipset chips, etc.) so that the operating system can operate the mboard as it was intended to run.
For Windows, that's straight forward - my standard spiel...
"Whenever you load Windows from a regular Windows CD (or DVD) from scratch, after Setup is finished you must load the drivers for the mboard, particularly the main chipset drivers, in order for Windows to have the proper drivers for and information about your mboard hardware, including it's AGP or PCI-E, ACPI, and hard drive controller support. If you have a generic system and have the CD that came with the mboard, all the necessary drivers are on it. If you load drivers from the web, brand name system builders and mboard makers often DO NOT have the main chipset drivers listed in the downloads for your model - in that case you must go to the maker of the main chipset's web site, get the drivers, and load them."
I know very little about MAC operating systems.
For a MAC operating system, what you need to load may also be on the CD that came with the mboard too, or you may need to go to the web site of the mboard maker and get MAC drivers for the model, etc., and load them and/or you may need to go to the web site of the main chipset maker and get MAC drivers, etc., and load them.
- all the hard and optical drives will often have a slower sustained and maximum data transfer speed if the operating system does not have the proper info about the drive controllers on the mboard.
- USB 2.0 has much faster max data transfer speeds than USB 1.x. All modern operating systems (since Win 95 OSR2 in Window's case) will automatically detect and support USB 1.1, but they may NOT detect USB 2.0 support automatically.
More recent mboards (since about 2002) have USB 2.0 controllers built in - they are backward compatible with USB 1.1 standards, so if your operating system recognizes the USB 2.0 controllers properly, it sees both USB 1.1 support and USB 2.0 support.
For Windows XP, it did not have support built in for USB 2.0 when it was first released - support for that was added when SP1 updates came out - but even if XP has SP1 or SP2 or SP3 built in, or added on after you run Setup, you MUST load the drivers and info (Windows main chipset "drivers" are often mostly *.inf files that tell Windows how to use the mboard hardware using support already built into Windows) for the mboard's main chipset, otherwise the operating system does NOT recognize the USB 2.0 controllers on the mboard and install support for them - the operating system sees only the USB 1.1 component of the USB 2.0 hardware on the mboard.
E.g. on a computer I have, mboard made about 2003, after the main chipset drivers and info for the mboard have been loaded, in Windows XP with SP2 updates, in Device Manager, under the heading "Universal Serial Bus Controllers", USB 2.0 controller support shows up as "Via USB Enhanced Host Controller"
The labelling varies according to the make of the main chipset on the mboard, but you get the gist,
The operating system must recognize the USB 2.0 controller(s) is(are) there and have the support for that installed in order for it to be able to support USB 2.0 data transfer speeds of USB devices that can use the enhanced USB 2.0 data speeds.
(the USB 1.1 controller support shows up there as four instances of "Via Rev 5 or later USB Universal Host Controller"
- you may be comparing apples to oranges regarding which programs you are using when you note how fast the data transfer speed is, and whether they are actually using the operating system or are booting into a different operating system in order to support the program. The support must be there to support the USB 2.0 capabiliities, otherwise the data transfer speeds will be that for USB 1.0 (the slowest standard) or USB 1.1 (slow).
"Do you know of any apps that can tell me what is accessing the drive?"
For a MAC operating system - NO. I know very little about MAC operating systems.
In Windows, there are third party programs you can use (e.g. Process Explorer, available on the Microsoft web site), and there are some things built into Windows you can use or look at. E.g. problems with a device MAY be flagged in Device Manager with a yellow ? (question mark) or with a red circle with a white X in it, and in System Information, there MAY be something on the left side under Components - Problem Devices
I don't know of anything that would affect the max data transfer speed of one external hard drive and not another external hard drive, if they are both plugged into USB ports they should work properly in, when compared in the same operating system using the same program, outside of one having a defective or inadequate USB cable.
Do you have other USB cables to try between the drive and the USB port? If one came with the drive, it should work fine, but if you had to buy it separately, it should be rated to support USB 2.0. A USB cable that is not rated to support USB 2.0 MAY work properly, but it MAY NOT - if it is rated to support USB 2.0 it will for sure.
It's not hard to damage USB cables, especially if you pull on the cord instead of the connector when you unplug them - try another USB cable if in doubt.
If the one external drive was always slower it could be the circuits inside the drive's enclosure are defective, or the USB cable is defective or inadequate, or the power adapter to the external case is not working properly, but since it appears it works fine in Windows, that's not your case.