Now I could be wrong here, because I’m not a bus architect, but I don’t think spreading the ram out matters. Its all on the same bus. I would think fewer chips in fewer slots would allow for expansion in the future. (unless I missed where one chipset offers lots of bays and the other doesn’t). But bigger chips are more expensive than smaller ones. At least until you throw the small ones out completely when you need those slots back and more Ram.
The big thing here is how else do you want to use the machine. And this comes down to cores. For 3D apps you want to allow enough ram so that each core can have enough RAM to take its part of the render. Watching C4D cook is really cool when you have a whack of cores. 12, 16 or 32 little renders going on simultaneously all over the image, each one being done on a separate core. But its only efficient if you have enough ram to support those cores.
For AE, the rule of thumb has always been: Faster CPU clock speed at the sacrifice of core numbers. Its common when you get a lot of cores in a chip that you don’t get the top speed available in that chip set. I’m not sure if this is an issue with dumping heat, or the way the cores are optolithographied means the accuracies aren’t as good so you have to run at a slower speed, or its just that the info from all those cores spitting things out all at once gangs up on the bus and you just have to slow it all down to get everyone on board. But based on experience and (what might now be old thinking) its better to have a faster overall speed than a slower speed and many cores.
Keep in mind too that much of what after effects does can be shunted to the video card. So lots of ram there too is best because compared to a video card’s speed, your processor is standing still. Put the render on the fastest proc.
There’s lots of discussions on the boards about what vid card is best. Some play well with after effects and some don’t. Again this is a confusing mess because the pro cards (the Quadros) seem on the surface to be slower but in practice they tend to produce faster results, or should I say fa$ter. Whereas the GTX and Titanium cards: the 900s and 1000 series, look faster, with their gobs of cuda cores but can actually be slower, and worse, incompatible – I’ve got a 970 and 980 that work great but won’t let me play smooth video out of cached AE. We’ve never solved it.
Then there’s the drive. Ae must have fast drives as it’s always shunting stuff to cache that it can’t fit in ram – and it can never never never fit it all in ram. So consider an SSD somewhere in the mix. Some say use it for your disk cache some say use it for the OS and App since there are a lot of instructions getting passed around. I’m not sure, but keep in mind the SSD’s do have a finite number of read write cycles. We do a lot of 3D here and I’d hate to think how many times Maya or C4D writes to the drive every render – billions I would guess. It would trash an SSD in short order I would imagine. So we just use 7200’s and 10k drives while we wait for SSD’s to mature (and get cheaper).