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That may depend on what motherboard is used and how many memory slot there are in total ... 2, 3 , or 4. Generally speaking, though, it is usually the left most slot when looking at the motherboard mounted in the computer. To properly install the 2 memory modules, it would be helpful to know how many memory slots are on the motherboard.
As a side note, the motherboard in my present computer has 4 memory slots and none are 0. They are numbered 1 through 4 and this is a dual channel system. But, on my old computer there is an 0 slot but then it has 3 slots on a single channel system.
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