Re: Problems with new hard drive
For the diagnostics, you'll need to change options in your BIOS. Look for the SATA configuration, and change the setting from AHCI/RAID to IDE/Legacy.
Run the tests, and before you run back in Windows, CHANGE the settings back, or you'll be scared when it'll BSOD on you.
If it's still slow to the new drives, the 250GB HDD doesn't have anything to do with it. It could be your AV that's acting up, like scans and stuff, but I'd doubt it. Try transferring in Safe mode, see if it could be an application ruining the nice transfer speeds.