hard drive

i have a HP a324y desktop. about a month ago i added a 500gb WD harddrive
along with an existing 40gb WD drive. The 40 gig is jumpered at cs and the
added drive is jumped to the 2nd 2 pins. all worked well. I wanted to upgrade
the memory. The 2 new 512gb memory 1 worked 1 did not. At start up it kept
cycling at startup. To condense the story i replaced the bad pc. When i got
the new stick the computer starts and freezes on hp invent logo. After
playing for some time I removed the 2nd hard drive and all works well. I
called and got the hard drive replace thinking that was the problem. The new
1 also does the same. I tried moving jumpers, and also changed the ribbon
cable. Works well until I plug in the 2nd drive. Any one have any thoughts?
Thank you much.