agp 8x card in a 4x slot

Without thinking I ordered a gigabyte ati 9550 video card for my sisters computer I built for here last year. It has a msi km2m comb L. It has onboard video but does have a 4x agp slot. From what I understand the msi has a version 2.0 slot and the card I bought is a 3.0. I read that the voltage is different. I have also read that the 3.0 is backward comptable and will work with 1.5v and the 0.8volt. Has anyone used a 8x card in a 4x slot. I hope it will work, if not I have a spare video card! thanks for any help sm.

 

I have. I used my 9500 Pro in a 4x agp slot on my Soyo MB,

 

I figured I would try in one of my computers so put it in a ecs k7s5a which has a 4x slot. I am pretty sure if it did not work in this oldie but goodie I was probably out of luck. Well it worked just fine. Much better than the gforce 2 that is in there. So I will now try it in my sisters rig, and hopefully get the same results...............thanks for the reply Bill.