He's worried about the card blocking the connectors.
TBH, I think all your long term probs could be solved with a new mobo, you can get a 780G
for less than $75, your HD 4670 is a decent card, surely it can carry you over until you can get another one?
And with the new motherboard, you'd be able to choose whatever card you want, no matter what the size. You could overclock your current CPU so you wouldn't have to buy a new one, and if you did, you'd have support for the new Phenoms etc.
If I were you I'd definitely upgrade the mobo before the GPU.