I've looked at a lot of photos and done extensive parts shopping for both, but I'm currently in the R620 environment, and looking to upgrade to the R630 environment in the future for power savings and to preempt aging hardware. But something continues to occur to me and I can't find an answer online, and it seems it would have been asked and tested and answered a dozen times by now but it hasn't been.

Can you effectively upgrade an R620 to an R630 by replacing the Motherboard, plus the CPU and RAM? AFAICT, the chassis are identical. The MOBO layouts are identical. The Fan configurations are identical. The PSU size and placement are identical (Though with different wattage options). Even the backplanes and front panel connections seem identical after looking at dozens of photos of R630s and comparing them to my own R620s. However, I can't physically take an R630 motherboard and put it into an R620 right now. But if I could, that would be a sweet, cost-saving way to work the upgrade process. So, does it work? Is it possible? Or is there some subtle differences that don't show in the pictures that make it impossible?

Now of course I'm sure I'll get some people saying "Of course it is(n't) because..." without actually trying, and maybe a dell employee saying "it isn't supported". I don't really care for speculation. I've gone through layers of speculation, and if I cared about support, I wouldn't be shopping on ebay for parts ;) I want to hear from somebody whose tried or, or somebody who has had both side by side and was like "Oh, there's the difference! That's why it wouldn't work..." or the like. Of course I welcome the speculation, it's fun to dream, but I want a definitive answer from someone whose tried it, or at least investigated far enough to know for sure it wouldn't work, and why