I don't know a whole lot about technical stuff, but I can say that the white objects appear for me occasionally. It's not a big deal though because the textures pop up in a couple seconds, sometimes up to 10 or 15 seconds for larger houses. It especially happens when I play one family and I visit another sim's large house with them.
The thing that does catch my eye is your amount of memory, though. That much RAM equals 12 gigs (I think) and that's a huge amount. If you really do have that much RAM then there is absolutely no reason for the white objects to show up. I'm assuming they show up when your computer is too slow and needs to catch up with what's loading. You seem to have an adequate processor and video card, so that's not the problem.
I did just Google your computer, though and it comes with only 4 gigs of RAM. Did you have additional RAM put in? I'm asking because if it just turns out to be a technical mistake about Memory: 12288MB RAM, then the reason your game is having the white objects is that it just needs a few seconds to catch up.
Once again though, I'm not the most technical person, but these are just my thoughts on the matter. I hope they can help you.