General question regarding resistors and soldered RAM

[asussucks]

Hello there!
I'm curious to know what would happen if you moved the resistors to the other location while viewing a DIMM_SEL in the schematics.
i know if you move all of them to the other location you will be effectively disabling the onboard memory.

but im curious to know what would happen if you ONLY do it for specific ones?

i have a bad ram chip on a laptop motherboard and id rather be able to use that laptop than paying 500 bucks for a new motherboard. and im not good with soldering ram so im not gonna attempt to fix it that way. (not that i know which ram chip is bad anyways.)

so yeah what would happen if you only switch SOME of them off?

Thank you for your help

[Sebastian163]

Don’t do it, that’s not a good way to fix your issue. Try to remove the ram with hot air and flux it’s not that hard actually.

[asussucks]

Don’t do it, that’s not a good way to fix your issue. Try to remove the ram with hot air and flux it’s not that hard actually.

well actually. i have no idea which one is the broken one.

and i dont know how to figure that out. and once its removed i cant put it back on because i dont have a stencil. and i also dont have the paste for it.

i just wish to disable a part of the ram .. maybe BIOS change??

[m1ch43lzm]

i just wish to disable a part of the ram .. maybe BIOS change??

That only works if the board has additional RAM slot, you disable all the onboard RAM with a BIOS mod, or in some boards, changing resistor straps, and use only the external RAM

But if the board doesn't have a RAM slot (all RAM is soldered), can't do anything except replacing/reballing all 4 RAM chips, as trying to find the single faulty chip is very difficult

i know if you move all of them to the other location you will be effectively disabling the onboard memory.

but im curious to know what would happen if you ONLY do it for specific ones?

It depends, usually those resistors also select between different RAM vendors, such as Samsung, SK Hynix, Micron, etc, it's for loading the specific RAM timings for each RAM vendor, example: SK Hynix RAM may not like Samsung timings
Only in case you got the model with the highest RAM capacity, there may be a combination for half the RAM amount and same vendor, if the laptop was sold with that specs
Example: you have the 16GB model, but a 8GB model was also sold, there may be a table in the schematics related to ram capacity/brand, but without the full schematics I don't know which resistors to move, and there's a chance it won't work depending which RAM addresses are faulty...

[asussucks]

That only works if the board has additional RAM slot, you disable all the onboard RAM with a BIOS mod, or in some boards, changing resistor straps, and use only the external RAM

But if the board doesn't have a RAM slot (all RAM is soldered), can't do anything except replacing/reballing all 4 RAM chips, as trying to find the single faulty chip is very difficult



It depends, usually those resistors also select between different RAM vendors, such as Samsung, SK Hynix, Micron, etc, it's for loading the specific RAM timings for each RAM vendor, example: SK Hynix RAM may not like Samsung timings
Only in case you got the model with the highest RAM capacity, there may be a combination for half the RAM amount and same vendor, if the laptop was sold with that specs
Example: you have the 16GB model, but a 8GB model was also sold, there may be a table in the schematics related to ram capacity/brand, but without the full schematics I don't know which resistors to move, and there's a chance it won't work depending which RAM addresses are faulty...

oh nice. yeah it was sold with an 8gb variant. same motherboard. and i am sure i can find the schematics for it too. if i found it for this one im pretty sure i can find it for the other one.

so what you're saying is. if i switch them to be the same as the ones in the 8gb variant ill possibly be able to run it with 8gbs instead. correct?

[m1ch43lzm]

https://www.badcaps.net/forum/troubl...77#post1825577

From your screenshot is this one, right?
Take note of the positions of DIMM_SEL2, DIMM_SEL1, DIMM_SEL0, which resistors are populated, if a resistor is connected to +3VSUS equals "1", if its connected to GND equals "0"

Example:
For DIMM_SEL2 there are 2 resistors, R2105 and R2106; R2105 connects DIMM_SEL2 to GND and R2106 connects DIMM_SEL2 to +3VSUS, if R2105 is populated (and R2106 should be empty=, you have a "0"
For DIMM_SEL1 R2103 goes to GND "0", and R2104 goes to +3VSUS "1"
For DIMM_SEL0 R2101 goes to GND "0", and R2102 goes to +3VSUS "1"

Now make a note of the initial value of DIMM_SEL2, DIMM_SEL1 and DIMM_SEL0, example: 001
Try moving DIMM_SEL2 from R2105 to R2106, now you have 101, check if it powers on, and if it does, check the reported RAM capacity


The above table is taken from a different ASUS board, no guarantee it's the same for yours as the schematic diagram is not available for the X7400PC, only the boardview, there are 6 valid combinations depending on capacity and vendor
The other option, is to find a closeup picture of the same area for the 8GB motherboard, you'll notice the position of the resistors is different

No guarantee that it will work, proceed at your own risk