Strange first gen intel board? how does this ram config work?

herb · December 15, 2022

hi so recently i bought an Asus p7f7-e ws supercomputer motherboard because i like to collect weird hardware of the past. the thing that drew me to this board in particular is that it is a first gen motherboard that natively supports both core and xeon cpus and ECC RAM on a consumer platform. But the #1 thing that made me buy this is the REALLY strange ram setup. This motherboard has 6 ram slots, that might not sound strange but this isn't an x58 board. These are lga 1156 cpus which means they only have ram channels for 4 dimms. My question is how does this work? if the cpus were never designed to handle this many dimms how did asus make it work? id love to know for the sake of preserving the history of this board.

i am reasonably well versed in computer hardware so i do have a theory of my own. my theory is that the blue slots on the motherboard function like you would expect, 2 dimms per channel for a nice dual channel setup. my theory for the black slots is that they work in pairs. So the pairs of slots would almost function like a single stick that is a dual rank dimm. this might not be the case of course since dual rank dimms would have existed back then but that my best guess as to how they could allocate more to less.

Please let me know your thoughts as this is a super cool piece of history!!

mariushm · December 15, 2022

So it seems the motherboard has some hacks or something that make it possible to use 6 SS sticks only on processors from the Lynnfield family :

Wikipedia says these cpus are from Lynnfield family : https://en.wikipedia.org/wiki/Lynnfield_(microprocessor)

The manual explains how to populate the ram slots : https://dlcdnets.asus.com/pub/ASUS/mb/LGA1156/P7F7-E_WS_Supercomputer/Manual/e5403_P7F7-E_WS_Supercomputer.zip

At pages 2-11 and 2-12 you have the details :

So basically don't use A3 and B3

SS = Single Sided ... usually sticks that have ram chips only on one side, but NOT always. Safest best would be to say 2 GB DDR3 and majority of 4 GB DDR3 sticks with only 8 chips that are 8 bit wide on them would be SS ... anything else is not guaranteed to be SS.

edit : ECC sticks would have a 9th chip on them, or 1 extra chip for every 8 chips, to provide that ECC support.

You can have sticks made with chips that are 4 bit wide, and then to have a 64 bit wide stick, some manufacturers used 16 chips, and that was still as SS stick but the chips could have been on both sides of the stick. Intel processors were picky about such sticks though, often you find such ram sticks advertised as "for AMD" because AMD processors support a wider range of chip configurations.

herb · December 15, 2022

5 minutes ago, mariushm said:

So it seems the motherboard has some hacks or something that make it possible to use 6 SS sticks only on processors from the Lynnfield family :

Wikipedia says these cpus are from Lynnfield family : https://en.wikipedia.org/wiki/Lynnfield_(microprocessor)

The manual explains how to populate the ram slots : https://dlcdnets.asus.com/pub/ASUS/mb/LGA1156/P7F7-E_WS_Supercomputer/Manual/e5403_P7F7-E_WS_Supercomputer.zip

At pages 2-11 and 2-12 you have the details :

So basically don't use A3 and B3

SS = Single Sided ... usually sticks that have ram chips only on one side, but NOT always. Safest best would be to say 2 GB DDR3 and majority of 4 GB DDR3 sticks with only 8 chips that are 8 bit wide on them would be SS ... anything else is not guaranteed to be SS.

edit : ECC sticks would have a 9th chip on them, or 1 extra chip for every 8 chips, to provide that ECC support.

You can have sticks made with chips that are 4 bit wide, and then to have a 64 bit wide stick, some manufacturers used 16 chips, and that was still as SS stick but the chips could have been on both sides of the stick. Intel processors were picky about such sticks though, often you find such ram sticks advertised as "for AMD" because AMD processors support a wider range of chip configurations.