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- Help! Z840 929-Fatal MCA error
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12-12-2023 04:37 AM
Hi, when switching user, the system rebooted and then post came up with the following error:
929-Fatal MCA error
CBO/LLC1 error detected on CPU 0
Core 16777216 Data L2 cache data read error - uncorrectable data
CPU: 0
Status: 0xBE20000000000051136
Misc: 0x50F0083041401086
Address: 0x00000000000000B82C0
Please note this PC also has the following problem:
complete freeze with no sign of life once every 2 weeks now becoming more frequent once every 3-5 days. They happen randomly sometimes browsing files using explorer, browsing firefox, or sometimes when running Photoshops.
Nothing is shown in the logs.
Any ideas?
This is a Z840 with dual CPU with 128Gb ram and 1080Geforce card.
12-12-2023 09:02 AM - edited 12-12-2023 09:05 AM
the most common cause for this error is failing memory, remove all ram from the cpu 0 sockets in order, clean the ram contacts with 99% isopropyl alcohol then spray the contacts with contact cleaner and reinsert the ram
DO NOT USE TV CONTACT CLEANER, IT WILL CREATE MORE PROBLEMS
i recommend
https://caig.com/product/deoxit-gold-g5s-6/
or
https://caig.com/deoxit-d-series/
you can also replace the ram in cpu sockets with new modules
second cause is a failing CPU or bad contacts on cpu socket (unlikely but possible)
if cleaning/replacing ram does not resolve issue, try cleaning cpu/cpu contacts with deoxit spray (do not touch cpu pins!)
if all of the above fails, replace cpu (use same or newer cpu stepping!!)
Edit: also cleaning the video card contacts/pci-e socket and any other pci-e cards is strongly recommended as a poor pci-e card connection can also cause this 929 error
12-12-2023 10:58 AM
Thanks, I was worried it could be a mobo or gpu issue.
Could dirty contacts also be the cause for the recurring system freezes I’m having?
p.s. I run it memtest86 and it didn’t spot any problem with the memory, it could be a false negative?
Also, in regard to the freezes, I took out half the memory and still had a freeze 2 weeks later. But I can tear everything again once I clean all the contacts.
I think i’ll clean the cpu contacts and repaste as well.
I have both the wd40 contact cleaner and isopropyl alcohol. Could I use the latter?
out of curiosity why not the wd40 contact cleaner? I was using it recently on the pcb components of a vintage music keyboard, should I stop?
Thanks
12-12-2023 10:59 AM
Thanks, I was worried it could be a mobo or gpu issue.
Could dirty contacts also be the cause for the recurring system freezes I’m having?
p.s. I run it memtest86 months ago and it didn’t spot any problem with the memory, but could it be a false negative?
Also, in regard to the freezes, I took out half the memory and still had a freeze 2 weeks later. But I can tear everything again once I clean all the contacts.
I think i’ll clean the cpu contacts and repaste as well.
I have both the wd40 contact cleaner and isopropyl alcohol. Could I use the latter?
out of curiosity why not the wd40 contact cleaner? I was using it recently on the pcb components of a vintage music keyboard, should I stop?
Thanks
12-14-2023 11:00 PM
sigh,............can you use products not made to the task required?
sure you can, although i expect the results will be similar to using a hammer to extract a tooth IE- SUBOPTIMAL!!
wd 40 is not really designed to clean PC contacts such as those used in a cpu socket, like tv tuner spray it will leave a residue that actually causes more issues by trapping any dust on the item you use it on
and isopropyl alcohol that is less than 90% will not clean dimm contacts well and will not break down any existing oxidants' that have formed on the surface
01-08-2024 05:42 PM
Thanks!
I found this one in my country:
https://www.hotroxuk.com/caig-deoxit-d5-contact-cleaner-142-g-5-0-oz-d5.html
which i’ll order via amazon. Is the d5 ok against the gold or any other d series?
the d5 has more solvent which takes longer to dry I think.