Unusual Keyboard Issue & RAM Failure on Laptop

[DWDYEM2001]

Hello,

I'm having a strange problem with my current laptop (Model Samsung NP900x4C-07US); and also having a very hard time diagnosing the problem. I'm really hoping that this forum could help me as there are some smarter people than me in here.

Here's what's happening:

A month ago, I noticed that when my system was under heavy load (running warm & using lots of resources), that a three or four keys ("y" "k" "h") on my keyboard wouldn't function properly. By that, II mean that the key I typed wouldn't input the letter when I pressed the key. However, if I pressed it a few times it eventually would input the letter on the screen. Also, if I held the key down for a while, it would eventually type the letter.

However, this issue only seems to show up the computer has been running in Windows for a little while. When it does seem to randomly show up, just closing some programs (or restarting the system) would resolve the issue immediately. Right now I am having no problems at all with it while typing this post because the system hasn't been running for that long.

Again, The strange part about this is that it doesn't happen all the time. It only seems to happen after windows has been running for a while (w/o a power down) & when the RAM and CPU was under heavy load. Also, it's just a few keys (and always the same ones)

What I've tried in order to diagnose:
1. I tried plugging a USB keyboard in when the problem arises. USB keyboard worked fine.
2. I also tried using the on-screen keyboard when the problem arises. On-screen keyboard worked.
3. I also tried resetting the keyboard ribbon to the motherboard.
4. I also tried deleting the keyboard driver and restarting.
Note: There is no specific keyboard driver from the manufacturer for this laptop

Based on this, on paper, one might think the keyboard is bad.

However, I am still not 100% sure the keyboard is what needs to be replaced. The reason being is that only happens at random times when the laptop is under heavy load (and it runs warm/hotter). There also doesn't seem to be any problem with the with the responsiveness of the keys when it's not happening. Everything works exactly like it should when the problem isn't occuring. But whenever I start loading a bunch of tabs and a few resource intensive programs, it sporadically comes back and articles I type end up having words without the "y" "k" "h" and "v" letters in them.

I thought perhaps it might be due to a RAM issue, motherboard, or CPU issue.

So, I also tried;

1. I tried re-seating the ram in their slots.
2. I did a windows memory test and it resulted in some errors
3. I also did a RAM test with MEMTEST86 and it resulted in 101 errors.
Note: I never have any issues with blue screens, restarts, or anything of that nature.

Replacing the keyboard on this laptop isn't as simple as buying just a keyboard due to the design of this system. It would require a new base assembly for over $200 and a complete breakdown of all the components. Additionally replacing 16gb of laptop ram isn't cheap either (as it seems I am having RAM).

So, I really want to properly diagnosing the problem (if only one) before I make any decisions to buy different parts (to repair it); or decide to go buy a new laptop all together (if it's more cost effective).

Does anyone have any suggestions as to how I should proceed in order to make a proper decision and not blow money on a different laptop. I also really love this laptop and don't want a new system with shitty windows 10.

Thank you so much in advance. This forum is great.

 

[DRDNA]

I dont know about the keyboard but everything else you described sounds just like laptop throttle issue.... You can confirm this with CPU-Z or MSI Afterburner or even Intel s XTU app. Possible the keyboard issue is because of CPU throttling as well.
If it is throttling and has not before then maybe it needs a good dusting on the heatsync just be careful of the internal fan...

 

[Mussels]

laptop keyboards have a thin ribbon cable running to the mainboard, its possible yours is the tiniest bit loose, and adding in heat for some reason pushes it further out (expansion/contraction, blood magic, whatever)

Cant speak for your laptop specifically, but normally its pretty easy to lever a keyboard out and check the cable to it

 

[hat]

You said the keyboard only malfunctions when the system heats up under heavy load. I can't be sure exactly what's happening, but it seems clear to me that the root cause of this is the heat is affecting some things. Your best bet would probably be to keep the laptop cooler somehow. I'm sure you've probably already cleaned the system of heat trapping dust, since you mentioned you re-seated the keyboard cable.

Depending on how well you cleaned it, it's possible there's still dust lingering around in the system in hard to reach places that won't be effectively cleaned by simply blowing canned air through the slots. You may need to tear the laptop down a bit and clean it more thoroughly. It's also possible removing the heatsink, cleaning it up with rubbing alcohol and a lint free cloth (coffee filters work for this, also toilet paper is okay for mopping up excess paste) and applying fresh paste might help (I usually recommend Arctic Cooling MX-4). You may want to invest in a laptop cooling pad.

As for the RAM, you mentioned memtest86 produced errors. That means the RAM is bad... even if it only throws a single error, it's bad, short of the inconceivably small possibility your laptop got hit by a cosmic ray of some type and flipped a bit during the test. It could also mean there is something wrong with the memory controller, but that's far less likely than simple bad RAM. It's also possible heat generated during the test is responsible for the error... it would be worth re-running the test once the laptop is running under cooler conditions.

 

[DWDYEM2001]

It sometimes happens when the laptop isn't running super warm.

The issues are strange.

Example:
I can type a lowercase "f", but not an uppercase one "shift + f"
At the same time, I can type other uppercase letters just fine.
So, the shift key is working fine.

Maybe I will try cleaning the heatsink. Perhaps the fan on the heatsink isn't operating properly.

Really having trouble with this.

 

[sneekypeet]

It sometimes happens when the laptop isn't running super warm.

The issues are strange.

Example:
I can type a lowercase "f", but not an uppercase one "shift + f"
At the same time, I can type other uppercase letters just fine.
So, the shift key is working fine.

Maybe I will try cleaning the heatsink. Perhaps the fan on the heatsink isn't operating properly.

Really having trouble with this.

Have you tried this with both Shift keys to rule out some funky anti-ghosting issue in the keyboard?

 

[DWDYEM2001]

Have you tried this with both Shift keys to rule out some funky anti-ghosting issue in the keyboard?

Thanks for the response.

Yes, I believe I have. I will check the next time the issue arises. What do you mean by "anti ghosing issue"?

Any chance this could be caused by a MB that is going bad??

I really don't want to get into a guessing game with the hardware that needs to be replaced and waste money (which is tight at the moment). I'm not noticing anything consistent with regard to the CPU usage or RAM usage when it happens.

When it does happen, it seems to happen with these keys only: "y", "h", "k", "x". Also, when it does happen if I cycle through those keys (tapping them each a couple times) all the keys start working again.

This happens even when I don't even move the laptop from the surface it's on, which makes me think it's not an issue with the keyboard at all (but another component like the MB or RAM)

Any other suggestions to narrow it down, please let me know.

It is seriously driving me mad trying to diagnose this.

 

[sneekypeet]

What do you mean by "anti ghosing issue"?

Anti-ghosting is the inability of a keyboard to register all/multiple/certain key strokes or combinations of keys.

 

[DWDYEM2001]

I also tried booting to Linux and I don't notice the problem at all.

I am wondering if something corrupted in windows could be causing the problem.