Memtest86 , How long should test run?

[Hunter]

I ran memtest86 v.3, all nite, on my 1.5 yr old Crucial 256mb DDR and discovered errors on test #7 . Tried it on both slots in my K7S5A v.1x . So, i picked up a new stick of same Crucial. Its been running tests for 3 hrs.without errors.
How long do I need to run the tests to know the ram's good to go , and start putting my pc back in order.
I had changed to a different vid card thinking that was my problem with lockups. Do I need to run the mem test with the old vid card since I plan on using it?
I've never done an RMA before. Is there anything I need to know or do before I call Crucial for an RMA? I've got the original packaging and reciepts.

[omega31]

2 links from the Crucial web site:
http://www.crucial.com/helpdesk/returns_policy.asp
http://www.crucial.com/helpdesk/returns.asp

You should run memtest86 for at least one pass through all the tests.

[Hunter]

Well, I'm happy. I ran the full test 4 times through , 12.5 hrs worth, without errors. I'm back in business. I'll follow the links to Crucial, Thanks.

[Bovon]

Hunter, just for kicks...if you can, without it getting in the way of daily use of the computer...stick the bad stick back in the machine and re run the test...just to see if that error shows up still..