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I have a very strange issue in running Ubuntu 16.04, 64 bit on my Dell Inspiron N5110, Bios version is A11.

Initially, the ram was 3gb (speed 1333)i.e 2gb + 1gb. I found the computer to be slow and so decided to upgrade the ram. I bought Corsair 8gb (speed 1600) ram.

So I installed the new ram by removing 1gb stick. The computer booted into both Ubuntu and Windows 7 (dual boot setup) properly. No issues. But when I tried to boot into Ubuntu the third time, the kernel went into panic and my capslock key was blinking. Sometimes, the screen would turn grey with no progress. I want to mention that I am able to boot into Windows 7 with no problem and even into Recovery menu of Ubuntu (i.e. Advanced boot options of Ubuntu).

Since addition of the RAM was the only last change I made, I removed the 8gb stick and it booted fine with 2gb stick in it. Then I tried to keep only 8gb and it booted fine. But when I tried to boot 3rd time, it again goes into kernel panic or grey screen. This time, I inserted the 2gb stick back again along with the 8gb stick already present. Voila, it booted fine. But just for 2 times. The third time, it again starts Capslock key blinking which means Kernel panic.

After observing this problem for sometime, I have concluded that the system needs changes in RAM configuration to boot fine once it goes into kernel panic.

E.g. a) If I am on 8gb+2gb and the issue starts then I will just remove either the 8gb stick or 2gb stick and it will boot fine for 2-3 times.

b) If I am on 8gb stick and the issue starts, I will simply add the other stick and it will boot fine.

The problem doesn't occur when only the 2gb stick that came with the laptop is present. As suggested, I have done memtest of both the rams and they have passed all tests i.e. no errors from memtest.

I am not sure what is causing this problem. Is it possible to resolve this problem? I am definitely sure the cause of the problem lies in have a ram with different speed i.e. 1600 Mhz rather than the one recommend i.e. 1333 Mhz. But what puzzles me is that the issue occurs only after two successful boots, the third time Ubuntu goes into kernel panic (Capslock key blinking or only grey sceen present).

user238607
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  • What happens if you boot into Ubuntu successfully twice and then try booting into Windows? Also, please try booting in verbose mode and attaching a picture of the kernel panic at crash. Alternatively, please try to find any logs to help guide us in a better direction. – Kaz Wolfe Oct 09 '16 at 07:35
  • I tried verbose mode. But when the issue occurs, it prints few messages on the screen and suddenly the screen goes blank. After rebooting, the capslock key starts blinking with blank screen. When the issue persists for Ubuntu, I am able to boot into Windows. I have tried this multiple times. Windows boot normal. Also, this issue has now started to occur ever alternate boot. So issue occurs, I add or remove a ram (usually 2gb) stick, it boots fine. But the second boot fails. I am able to boot into recovery just fine, no problem here. Looked at the kernel logs, there is nothing significant. – user238607 Oct 09 '16 at 09:59

1 Answers1

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RAM speeds are not dealt with by Ubuntu, therefore they shouldn't be a problem at all.

When your computer sees multiple different speeds of RAM present, the BIOS will scale down the speed of all of the RAM to the speed of the lowest RAM stick. In your case, that means all of you RAM will be running at 1333MHz. This is done automatically, before the Dell logo appears on your computer screen, and far before Ubuntu boots up.

This sounds more like your memory may be bad and/or mis-seated. Ensure that everything is connected properly, and then run memtest (from the GRUB menu) a few times to make sure that your RAM is okay. If a test fails, test each stick of RAM independently until you find the bad one, and then replace it.

If all of your memory returns okay, it's probably an issue with your computer's BIOS. Check to see if you have an upgrade available for it. A reset to default settings probably won't hurt either.

If your BIOS is completely up-to-date, it may be a good idea to contact Dell for further assistance.

Kaz Wolfe
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  • The memory isn't bad or mis-seated because whenever the problem occurs, I am able to boot into Windows 7 with no issues at all. The bios version A11 for Inspiron N5110 is the latest which I have. Also, as I pointed out the nature of the problem is predictable and reproducible. It would boot normally for 2 times and the third time, it goes blank. Change the ram config and it boots fine. If there had been problem with the bios then the problem should occur all the time and not just the third time. – user238607 Oct 09 '16 at 07:21
  • @user238607 Windows may be more resilient to memory errors in this case than Ubuntu. Have you tried resetting your BIOS settings to default or actually running memtest with the three-boot theory to see if anything is wrong? – Kaz Wolfe Oct 09 '16 at 07:29
  • I did complete memtest, both the rams passed all the tests. – user238607 Oct 09 '16 at 08:48
  • @user238607 Try resetting your BIOS settings to default as a last resort. If it still fails after this, there's something very strange and unexpected happening with Ubuntu. – Kaz Wolfe Oct 09 '16 at 16:23