Precision T1700 - Using ram slots

PC boards normally select the highest profile of the slowest available module. So, if the faster modules can work with slower profile, that's OK. But it is not always possible. Modern dimms have too many timing parameters, and it is easy to fall out of allowed operation range. Even when down-clocking. With buffered dimms it is easier, since logical pulse reactive smearing is compensated by these buffers, but it is not a panacea when down-clocking because the problem is not a pulse, but the refresh and row/col selection timing.

Do not mix modules of different voltage.

Do not put unbuffered dimms along with buffered, even if it seems mechanically possible.

Do not put very different unbuffered dimms in the same channel slots.

Avoid using dimms of different size/organization (ranks, per chip size).

Yes, all 4 slots will need the same type of RAM, Have the same voltage, and same Timmings, it is best to duplicate what you already have. or add 4 new matching Sticks that are known to work on your motherboard. This is why RAM is sold in 2x or 4x of matching sets

Will any of these other RAM Stick may or may not work, may knock out your ability to even boot. The correct paths for upgrading RAM are well known. Getting away from these protocols can and will have unknown results mostly none that are better.

Great information but I had this question about my T1700 about using three slots instead of four. Here I will copy and paste my last question as seen above.

I have only 1 stick of 12800 in my collection left. Can I use this for one slot and leave my other two slots populated for a total of 3 slots? Or do I have to have both extra slots populated so all four slots are used. Does this matter? I always thought that to populate 2 slots so they work together like dual channel? Or am I wrong about this?

If I don't get the right answer I will just go try it and stick one more stick in and leave one slot empty. I don't want to mix the speeds.