Installing DIMMs in the non-prefered slots--How much of a performance hit?

[elm43]

Hello everyone, I have a noob question. I know that when installing a pair of DIMMs on my mobo, there is a preferred set of 2 slots out of the 4 available in which to install them in order to get maximum performance. However, I plan to get two more DIMMs in the future (when my wife will let me shell out the $$$) to fill out all four slots. So the simple solution would be to put the 2 I have now in the preferred slots, and when I get the 2 others next year or whatever, it won't matter.

BUT, here comes the catch: my cpu heatsink partially covers the slots closest to the cpu, which happen to be the slots that are NOT the preferred slots. So if I install the 2 I have now in the preferred slots, I will not be able to install the other 2 later without taking of my heatsink and reinstalling it, which would be a pain. So I was thinking I would just install the 2 I have now in the non-preferred slots before I install the heatsink--but how much of a performance hit will I take for doing this? If it is noticeable, then I would rather just go through the pain of reinstalling the heatsink later. If it is negligible, then I can go with my initial plan.

Also, would there be any stability issues with doing this? I know it is not a big change, but I have been having issues with my mobo as is already (waiting for RMA at this moment) as have others in this forum, so I don't want to do even the slightest thing to give it an excuse to freeze up on me, (trust me--give this board any excuse and it will take it!).

Thanks Everyone.

ASrock 870 Extreme 3
AMD Phenom II x4 955 BE
4 GB Gskill DDR3-1333 F3-10666CL7D-4GBRH
HIS Radeon HD 6850 IceQX Turbo
XFX 650W PSU

[GSKILL TECH]

It just depends if it works or not (based on motherboard design). If it does, there should be no performance hit because it is still dual channel. So basically you'll have to try and hopefully it works.

Thank you
GSKILL TECH