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I don't think that will work. The MacPro uses ECC (error checking) ram. What you're looking at is Non-ECC . Here is a link to Crucial's 2010 Quad Mac Pro page. I've used them quite a few times and have never had any issues.
The link is to the U.S. Site but you can click over to the EU or British site in the upper right corner.

I hope you find this more helpful than the last post

http://www.crucial.com/store/listparts.aspx?model=Mac Pro Quad-Core MC250LL/A Mid 2010&Cat=RAM
 
Hi,
I looked into the ECC vs Non-ECC issue a little more. You can use Non-ECC ram in your MacPro but you can't mix and match ECC and Non-ECC sticks. So, if you were to buy Non-ECC ram you would have to get rid of the ECC ram that's already in your machine. This combined with the fact that error checking ram is preferable to non error checking ram, I would say just spend the extra money and get proper ECC ram. Also, it really isn't that much more expensive.
 
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