mapping of MemTest86 errors to a single chip

[rumpumpel1]

I would like to receive confirmation that the following considerations are correct:

I have a Lenovo ThinkPad T490s (NM-C891) with 16GB RAM (8 chips) soldered on the mainboard.
MemTest86 reports the following errors:
Lowest Error Address: 0x1F97B0930 (8087MB)
Highest Error Address: 0x1FB7B6DB0 (8119MB)

Dividing the 16GB into address ranges per chip I get the following table:
#1 0x000000000 - 0x07FFFFFFF
#2 0x080000000 - 0x0FFFFFFFF
#3 0x100000000 - 0x17FFFFFFF
#4 0x180000000 - 0x1FFFFFFFF
#5 0x200000000 - 0x27FFFFFFF
#6 0x280000000 - 0x2FFFFFFFF
#7 0x300000000 - 0x37FFFFFFF
#8 0x380000000 - 0x3FFFFFFFF

mapping the error addresses to chips indicates, that chip #4 is faulty.

ordering of the chips according the schematics:
SUB CHANNEL A: U3301 U3302 U3303 U3304
SUB CHANNEL B: U3501 U3502 U3504 U3503 (why this strange ordering?)

so the fourth chip would be U3304.

Looking at the mainboard shows the following (strange) ordering:
U3503 U3504 U3502 U3501 U3304 U3303 U3301 U3302

So I have to replace the fifth chip from the left. Is this correct?

[dggn]

Hello,
I have the same problem with this model. Was it possible to solve the fault ? Or maybe someone had such a problem and hints ?

[rumpumpel1]

So far I have not been able to solve the problem. I have tried using hot air and cold spray to locate the defective chip, but to no avail.

[pc_okay]

Hello don’t burn your brain for This,

if laptop work try LENOVO Hardware Diagnostic F10, it may be more accurate.
If not just change chips until it works and hope to be lucky !

ps: I don’t think cold spray Will help you in that case. you may use it only to locale short because short attract current and when a lot Of current pass in a component it heat.

good luck 😊