What is the maximum hard drive size that Win 7 Pro will support

I have Windows 7Professional, 64bit running on an SSD 500GB drive.

My internal drives are the 500GB SSD, 2 x 1TB, and a small 150GB velociraptor. My External drives, all powered, are 2 x 1TB, 2 x 500GB, and 2 x 2TB drives.

The newest one is one of the 2 TB ones. Since adding this one, I find I cannot run it if all the others are connected as well.

I read that there is a limit to how many TB Windows 7 can support, and that it depends also whether they are internal or external.

Please can you clarify this for me. If there is a limit, I will have to move a lot of data(photos) around so as not to need to run all at once.

I have also just upgraded the power pack to 650watts,quadrail.

Thanks.

No Windows 7 does not have a limit. Something else is limiting you, what it would be I'm not sure. Probably a limitation on the means you are connecting these external drives.

Is it initialized as GPT ?

Windows support for hard disks that are larger than 2 TB

If I am understanding the information given in the "support microsoft" link provided, if I initialize a 4TB (or larger) internal (or external) storage disk as GUID/GPT, then it matters not if the base firmware is BIOS so long as the boot disk agrees with the base firmware; .......... right ?

Yes.