Computer is HP 1037cb desktop with AMD 4 core processor (2011 vintage) with upgraded 16GB memory, graphics card, power supply and Cavalry 2 port USB 3 PCIe card. Original hard disk is a 1 TB Seagate with Windows 7 Home Premium installed. I added 2 external USB 3 hard drives - a 2 TB Iomega, and a 2 TB Seagate Free Agent GoFlex. This setup ran well with no problems. When Win 8 was released I added a second internal Western Digital 1 TB hard drive and installed the Win 8, then upgraded to Win 8.1 when it was released so I could boot to either Win 7 or Win 8.1. When I boot to Win 8.1 there is a problem with both USB 3 external disk drives. The external USB 3 Seagate drive goes into sleep mode about every 20 seconds, then wakes up again about 20 seconds later and keeps repeating this until shutdown. The external USB 3 Iomega does not go to sleep, but there is a series of audible beeps and disk activity every 20 seconds that repeats until shutdown. When I installed Win 8.1 the OS recognized the USB 3 card and installed Microsoft drivers. The Win 7 disk has drivers supplied by NEC Electronics and there are no USB 3 problems when running Win 7, only when running Win 8.1. I suspect the USB 3 card is incompatible with Win 8.1, but the Win 8 upgrade wizard did not detect any hardware incompatibility before installation. USB 3 cards are fairly inexpensive so I plan to try a different card. Has anyone else had any USB 3 problems in Win 8.1? Also if anyone has added a USB 3 card to an older computer and has no problems I would appreciate knowing what brand of card works. Thanks in advance.
P. S. - Sorry for double post - Don't see how to delete a post.
Edited by LeicaIIIf, 09 April 2014 - 02:05 PM.