How to configure 20 GB RAM?

[Maddler]

I had a bad 4GB chip of RAM from OWC, but the replacement just came in. So I need help in configuring the following:
(4) 4 GB chips
(4) 1 GB chips

I seem to remember there being a discrepancy in how to arrange pairs or quads between what Apple says and what barefeats says. Which is the correct way to ensure 256 bit addressing for my configuration?

[Tallest Skil]

The days when "20GB of RAM" is a typo are rapidly disappearing...

Top Riser: 4 4 1 1
Bottom: 4 4 1 1

So put the fours in the first two slots on each riser and the ones on the last two on each riser.

[kittiyut]

I had a bad 4GB chip of RAM from OWC, but the replacement just came in. So I need help in configuring the following:
(4) 4 GB chips
(4) 1 GB chips

I seem to remember there being a discrepancy in how to arrange pairs or quads between what Apple says and what barefeats says. Which is the correct way to ensure 256 bit addressing for my configuration?

Would you please share with us what you mean by "bad" ? I mean, what were the symptoms? Were all 4 "bad" ? How did you determine which ones were good? (assuming not all 4 were bad :)

I got 4 x 4GB from transintl added to my original 2 x 1GB for a total of 18GB.
My arrangment :

Top: 4 4 1 1
Bottom: 4 4

It seems like the top modules get hotter than the bottom...

KK