Question Computer frequently freezes (sort of) randomly, boots to blinking underscore

Feb 16, 2019
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Hi all,

First time on Tom's Hardware, made this account after browsing the forums for a solution to my issue, unfortunately to no avail. I am at my wits end, and would appreciate any help that anybody can offer.

I keep my computer on just about 24/7, and I am experiencing this frustrating issue where when I leave my computer for extended periods of time (such as when I am at work), my computer freezes.... sort of. When I return home, I will click the mouse or hit a button on my keyboard to wake the computer from sleep (as I always do), but nothing happens. The monitors remain off as if there is no signal, no amount of clicking or button pressing seems to wake it. Inevitably, I have to force restart my computer as even the reset button does nothing. When it eventually reboots, I see the mobo splash screen which then changes to a black screen with a blinking underscore. No matter how many times I reboot the machine, it will keep booting to the blinking underscore. I'm not sure exactly what fixes the issue, but eventually I will be able to boot to my OS. Occasionally when it finally boots to the desktop, while it's in the process of starting programs, the computer will completely freeze with no warning, and that starts the cycle over again (force restart, booting to blinking cursor, etc etc).

This is a new desktop I recently built (around the time of October 2018), however it is worth mentioning that I was experiencing this issue with my old computer as well, and part of the reason I invested in a new desktop was to finally be rid of this problem. So hopefully you can understand my frustration with the situation. Here is a list of all the parts in my desktop:

-Generic Dell USB keyboard/mouse
-2 Acer monitors (one connected via HDMI, one via DVI)
-Mobo: ASRock AB350 Pro4
-CPU: AMD Ryzen 7 2700x
-GPU: NVIDIA GeForce GTX 1070 (not sure if it matters but I think it was manufactured by MSI)
-Memory: 2x 8gb G.Skill sticks
-PSU: EVGA 750 P2
-HDD: SeaGate 2TB HDD
-Optical drive: Asus DRW-24B1ST

It's worth mentioning that I saved the optical drive and the HDD from my old desktop and used them in this new build. However, I only use the old HDD as a storage device, and bought a new SeaGate 2TB drive to install the OS on. I have tested disconnecting both the optical drive and the old HDD from the mobo to see if either were causing the issue, but still my problem persists. Initially, I saved the PSU from my old desktop to reuse in this one, but when this problem started cropping up, I was told to buy a new one (the one listed above). Again, this did not solve my problem, but I decided just to hold on to the new PSU either way.

I have tried every fix I could find on this website, Google, and through friend's suggestions. Here's a list of the fixes I have attempted:
-Buying a new PSU
-Disconnecting optical drive and storage HDD
-Disconnecting peripherals
-Fixing the MBR using a Win10 installation disk
-Running SeaGate's HDD diagnostic tool (passed all the tests I ran)
-Changed power settings to 'always on' (aka computer/monitors never get put to sleep)
-Replacing SATA cables

There are other things I have tried I am sure, but I am on my way out back to work so I can't quite recall everything at this moment. I had a friend who works in IT go through the Windows error logs during one such event (computer freezing, restarting, booting to a blinking underscore) and he found nothing unusual in the logs that might've indicated what the problem is.

One fix that was working for a little while was when such an event happened was I would shut down my computer, then would unplug the power cable from the PSU and press/hold the power button on the front panel for about 10sec to flush any static charge in the system (read this suggestion somewhere online, not sure exactly where). After that, I would plug the cable back in and press the power button again and my computer would boot normally. This sort of fix for sure would indicate a PSU problem in my opinion, but again I just replaced the PSU only a couple months ago. Now, this fix no longer works. Regardless of flushing the static charge, my computer still boots to a blinking underscore, and I usually have to wait at least a half an hour with the power cable unplugged before my desktop will boot normally, which is exceptionally frustrating.

Like I said, I am at my wits end. I dropped over $1.3k on this system, and to not even be able use it 80% of the time makes me want to rip all my hair out. If there is any additional information I can provide about my system or what I have done so far to diagnose the issue, please let me know and I will do my best to communicate that. Any and all help would be appreciated, because I have no clue what I can do at this point. Thanks for reading.
 
Jun 3, 2018
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Whenever that blinking underscore screen comes up there's an issue with your OS or the ability to read it. I've had the issue before and I had to disconnect my internal from the sata and data cables and plugged it back in (while system was off) and it read it just fine when I rebooted. As for consistently doing this I am not too aware of a fix for this. Try booting to safe mode and reading the diagnostics on the system. Make sure everything is clean and plugged in completely and securely. Try unplugging your hard drive and plugging it back in to make sure there's a secure connection but also to refresh the connection in the system.
 
When you see the blinking underscore that means that the motherboard's boot process is trying to hand over control to the boot device. If a boot device isn't detected then you'll keep seeing the blinking underscore.

An SSD is more preferable than an HDD for a boot device.
 
Jun 3, 2018
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3
35
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Hi all,

First time on Tom's Hardware, made this account after browsing the forums for a solution to my issue, unfortunately to no avail. I am at my wits end, and would appreciate any help that anybody can offer.

I keep my computer on just about 24/7, and I am experiencing this frustrating issue where when I leave my computer for extended periods of time (such as when I am at work), my computer freezes.... sort of. When I return home, I will click the mouse or hit a button on my keyboard to wake the computer from sleep (as I always do), but nothing happens. The monitors remain off as if there is no signal, no amount of clicking or button pressing seems to wake it. Inevitably, I have to force restart my computer as even the reset button does nothing. When it eventually reboots, I see the mobo splash screen which then changes to a black screen with a blinking underscore. No matter how many times I reboot the machine, it will keep booting to the blinking underscore. I'm not sure exactly what fixes the issue, but eventually I will be able to boot to my OS. Occasionally when it finally boots to the desktop, while it's in the process of starting programs, the computer will completely freeze with no warning, and that starts the cycle over again (force restart, booting to blinking cursor, etc etc).

This is a new desktop I recently built (around the time of October 2018), however it is worth mentioning that I was experiencing this issue with my old computer as well, and part of the reason I invested in a new desktop was to finally be rid of this problem. So hopefully you can understand my frustration with the situation. Here is a list of all the parts in my desktop:

-Generic Dell USB keyboard/mouse
-2 Acer monitors (one connected via HDMI, one via DVI)
-Mobo: ASRock AB350 Pro4
-CPU: AMD Ryzen 7 2700x
-GPU: NVIDIA GeForce GTX 1070 (not sure if it matters but I think it was manufactured by MSI)
-Memory: 2x 8gb G.Skill sticks
-PSU: EVGA 750 P2
-HDD: SeaGate 2TB HDD
-Optical drive: Asus DRW-24B1ST

It's worth mentioning that I saved the optical drive and the HDD from my old desktop and used them in this new build. However, I only use the old HDD as a storage device, and bought a new SeaGate 2TB drive to install the OS on. I have tested disconnecting both the optical drive and the old HDD from the mobo to see if either were causing the issue, but still my problem persists. Initially, I saved the PSU from my old desktop to reuse in this one, but when this problem started cropping up, I was told to buy a new one (the one listed above). Again, this did not solve my problem, but I decided just to hold on to the new PSU either way.

I have tried every fix I could find on this website, Google, and through friend's suggestions. Here's a list of the fixes I have attempted:
-Buying a new PSU
-Disconnecting optical drive and storage HDD
-Disconnecting peripherals
-Fixing the MBR using a Win10 installation disk
-Running SeaGate's HDD diagnostic tool (passed all the tests I ran)
-Changed power settings to 'always on' (aka computer/monitors never get put to sleep)
-Replacing SATA cables

There are other things I have tried I am sure, but I am on my way out back to work so I can't quite recall everything at this moment. I had a friend who works in IT go through the Windows error logs during one such event (computer freezing, restarting, booting to a blinking underscore) and he found nothing unusual in the logs that might've indicated what the problem is.

One fix that was working for a little while was when such an event happened was I would shut down my computer, then would unplug the power cable from the PSU and press/hold the power button on the front panel for about 10sec to flush any static charge in the system (read this suggestion somewhere online, not sure exactly where). After that, I would plug the cable back in and press the power button again and my computer would boot normally. This sort of fix for sure would indicate a PSU problem in my opinion, but again I just replaced the PSU only a couple months ago. Now, this fix no longer works. Regardless of flushing the static charge, my computer still boots to a blinking underscore, and I usually have to wait at least a half an hour with the power cable unplugged before my desktop will boot normally, which is exceptionally frustrating.

Like I said, I am at my wits end. I dropped over $1.3k on this system, and to not even be able use it 80% of the time makes me want to rip all my hair out. If there is any additional information I can provide about my system or what I have done so far to diagnose the issue, please let me know and I will do my best to communicate that. Any and all help would be appreciated, because I have no clue what I can do at this point. Thanks for reading.
After re-reading and doing some digging there's only a couple areas where you could have an issue.
  1. HDD is bad
  2. OS is corrupted
  3. Bad cable either sata or data
  4. Improper power to HDD
  5. Bad mobo (can't read OS properly)
These are the main things I could come up with. Of course I would start with examining everything and check for any bad wiring first as that would be the cheapest route for you. I would also make sure that the OS is taking up the proper percentage of the HDD or SSD. If you were to move the OS from one drive to another you have to adjust the setting so the OS takes up a certain percentage. I would check for this as well as adjusting the data ratio of the OS will cost you virtually nothing if you have access to another computer.
 
Feb 16, 2019
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Whenever that blinking underscore screen comes up there's an issue with your OS or the ability to read it. I've had the issue before and I had to disconnect my internal from the sata and data cables and plugged it back in (while system was off) and it read it just fine when I rebooted. As for consistently doing this I am not too aware of a fix for this. Try booting to safe mode and reading the diagnostics on the system. Make sure everything is clean and plugged in completely and securely. Try unplugging your hard drive and plugging it back in to make sure there's a secure connection but also to refresh the connection in the system.
I will give this a shot and report back. Cleaning and reseating everything is a good baseline to set going forward. In reference to your other post, I'm going to go through and make sure all the sata/data cables are brand new ones just to be sure. Are there any good diagnostics you would recommend to check if the HDD is bad? As I mentioned, I ran a few tests using SeaGate's diagnostic tool, and it passed all the tests I ran, but maybe there's a better tool I should be using. I'm a little confused by what you were saying about the OS taking up the proper percentage of the HDD, would you be able to explain that further or link a relevant resource? What's the best way of determining what percentage the OS is taking up?


When you see the blinking underscore that means that the motherboard's boot process is trying to hand over control to the boot device. If a boot device isn't detected then you'll keep seeing the blinking underscore.

An SSD is more preferable than an HDD for a boot device.
Yes, you're right. I'm kicking myself for not getting an SSD, but unfortunately I won't be able to buy one for a bit due to tight finances. Certainly something to keep in mind for the future though, so thank you for the suggestion.

Thank you all for the suggestions, I appreciate them very much!
 
Jun 3, 2018
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I will give this a shot and report back. Cleaning and reseating everything is a good baseline to set going forward. In reference to your other post, I'm going to go through and make sure all the sata/data cables are brand new ones just to be sure. Are there any good diagnostics you would recommend to check if the HDD is bad? As I mentioned, I ran a few tests using SeaGate's diagnostic tool, and it passed all the tests I ran, but maybe there's a better tool I should be using. I'm a little confused by what you were saying about the OS taking up the proper percentage of the HDD, would you be able to explain that further or link a relevant resource? What's the best way of determining what percentage the OS is taking up?




Yes, you're right. I'm kicking myself for not getting an SSD, but unfortunately I won't be able to buy one for a bit due to tight finances. Certainly something to keep in mind for the future though, so thank you for the suggestion.

Thank you all for the suggestions, I appreciate them very much!
Operating Systems take up a certain percentage of hard drives. Take for instance the specific OS takes up 13% of your 1TB HD (made up) it still needs to be taking up 13% of the next HDD even if it was a 2-3TB. Used to mod consoles with larger internal drives and this was a BIG thing in making sure OS works. You can find online diagnostic tools or if you boot up and go to safe mode (look up how, its mobo manufacturer specific on the hotkey) sometimes it's F11 or F14 when the mobo logo pops up. It should show a diagnostics screen where it'll show if it's having any issues. Also with the SSD you can get one pretty cheap. Just get one big enough for your OS to fit on. You should be able to find one for around $20, maybe less.
 
Feb 16, 2019
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Operating Systems take up a certain percentage of hard drives. Take for instance the specific OS takes up 13% of your 1TB HD (made up) it still needs to be taking up 13% of the next HDD even if it was a 2-3TB. Used to mod consoles with larger internal drives and this was a BIG thing in making sure OS works. You can find online diagnostic tools or if you boot up and go to safe mode (look up how, its mobo manufacturer specific on the hotkey) sometimes it's F11 or F14 when the mobo logo pops up. It should show a diagnostics screen where it'll show if it's having any issues. Also with the SSD you can get one pretty cheap. Just get one big enough for your OS to fit on. You should be able to find one for around $20, maybe less.
So I did a little digging and apparently my OS files take up 24.8gb of hard drive space. And after doing some research online, that seems about right for a Windows 10 64bit installation. I just got done cleaning/reseating all the parts in my desktop, as well as replacing all old SATA cables. So far so good, but as this was a problem that happened seemingly randomly, it might take a while for the problem to occur again. I will report back should any problems crop up, and in the meantime will search for some diagnostic tools as you recommended, thanks!
 
Jun 3, 2018
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So I did a little digging and apparently my OS files take up 24.8gb of hard drive space. And after doing some research online, that seems about right for a Windows 10 64bit installation. I just got done cleaning/reseating all the parts in my desktop, as well as replacing all old SATA cables. So far so good, but as this was a problem that happened seemingly randomly, it might take a while for the problem to occur again. I will report back should any problems crop up, and in the meantime will search for some diagnostic tools as you recommended, thanks!
No problem. I would also keep an eye on your core temperatures just to make sure nothing is overheating on you causing the freezing issues.
 
Feb 16, 2019
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No problem. I would also keep an eye on your core temperatures just to make sure nothing is overheating on you causing the freezing issues.
Okay, so it happened again last night. I went out to clean my car for about 15min, and when I came back my monitors had no signal and nothing I did would wake them. When I restarted, I was brought back to the blinking underscore screen 😣 An interesting note though, it didn't appear like my computer had frozen. I was playing a video game at the time, and had left it running. When I came back, even though the monitors had no signal, I could still hear noises from the game playing, and I was even able to fire off some rounds in-game. Not sure if that's useful information, but I thought I'd mention it.

I checked the core temperatures, and they seemed normal (around 95° F). Also, it was recommended to me that I turn off fast boot and hibernation mode, so I had my IT friend walk me through doing that. I also checked my boot order to make sure my HDD was booting first. I changed the ordering to make sure it was, but I also saw "UEFI" listed as one of the boot options. Should I be selecting that as my #1 boot priority? I thought I read that somewhere online, but I wasn't entirely sure.

I'm currently downloading my mobo's update app, and I will check to see if it needs any updates. I've been regularly installing all Win10 updates, but they don't seem to have any impact on my problem.
 
Jun 3, 2018
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Okay, so it happened again last night. I went out to clean my car for about 15min, and when I came back my monitors had no signal and nothing I did would wake them. When I restarted, I was brought back to the blinking underscore screen 😣 An interesting note though, it didn't appear like my computer had frozen. I was playing a video game at the time, and had left it running. When I came back, even though the monitors had no signal, I could still hear noises from the game playing, and I was even able to fire off some rounds in-game. Not sure if that's useful information, but I thought I'd mention it.

I checked the core temperatures, and they seemed normal (around 95° F). Also, it was recommended to me that I turn off fast boot and hibernation mode, so I had my IT friend walk me through doing that. I also checked my boot order to make sure my HDD was booting first. I changed the ordering to make sure it was, but I also saw "UEFI" listed as one of the boot options. Should I be selecting that as my #1 boot priority? I thought I read that somewhere online, but I wasn't entirely sure.

I'm currently downloading my mobo's update app, and I will check to see if it needs any updates. I've been regularly installing all Win10 updates, but they don't seem to have any impact on my problem.
Hm, I would go through your Mobo website and download all drivers and make sure everything is up to date as well as the drivers for your gpu which could be found on the gpu manufacturer website. Seems like something is causing a crash. Is your computer ever just on desktop with all programs closed when it crashes? Also you shouldn't have that other option as your boot priority as your os is on your HDD. Could be wrong since I've never actually seen what you're talking about but if your os is on your HDD that is what you would want to do. Another option (though a pain) is do a whole system wipe, including wiping your os and do anfeesh install of your os. Just in case your os got corrupted. This would of course be the last ditch effort in fixing this.
 
Feb 16, 2019
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Hm, I would go through your Mobo website and download all drivers and make sure everything is up to date as well as the drivers for your gpu which could be found on the gpu manufacturer website. Seems like something is causing a crash. Is your computer ever just on desktop with all programs closed when it crashes? Also you shouldn't have that other option as your boot priority as your os is on your HDD. Could be wrong since I've never actually seen what you're talking about but if your os is on your HDD that is what you would want to do. Another option (though a pain) is do a whole system wipe, including wiping your os and do anfeesh install of your os. Just in case your os got corrupted. This would of course be the last ditch effort in fixing this.
I actually did exactly this yesterday, updating everything I could via my mobo's website, including flashing the BIOS (which was a nightmare to do, but I'm glad I did it). Good call on updating GPU drivers though, I will do that as well. Yes, my computer has crashed without any programs open. Would that indicate a possible driver issue to you?
 
Jun 3, 2018
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I actually did exactly this yesterday, updating everything I could via my mobo's website, including flashing the BIOS (which was a nightmare to do, but I'm glad I did it). Good call on updating GPU drivers though, I will do that as well. Yes, my computer has crashed without any programs open. Would that indicate a possible driver issue to you?
Hm, I'm not sure. You did say this was happening with your old computer? What parts did you salvage off your old computer for this build? There has to be a cool theme going on if two different builds were doing it. It could be a possible driver issue and you should update those regardless to provide better stability. Is there any components you specifically kept out of your old computer though?
 
Jun 3, 2018
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I actually did exactly this yesterday, updating everything I could via my mobo's website, including flashing the BIOS (which was a nightmare to do, but I'm glad I did it). Good call on updating GPU drivers though, I will do that as well. Yes, my computer has crashed without any programs open. Would that indicate a possible driver issue to you?
Sorry, just read your post again. You said you kept your old HDD and got a new one for your OS. This could point to your old HDD as the issue since you say your old one did it too and this would be an HDD issue. Log onto your computer go to Start>my computer>{click on your old HDD storage drive}>properties>tools>{error checking} hit check. This will take a while but I honestly had the F1 to resume from S.M.A.R.T. status BAD until I did this the other day. If this does not help. Your HDD is bad. Could even be a possible virus in it so I would wipe everything including os, take out your old HDD, then reinstall your os on the one HDD you have in. Just make sure to get an 8gb minimum is drive and download the windows toolkit on it first so you can boot off of it. There's a lot of tutorials on how to do it and how to get your windows back so long as you have the key still. Or you can do free windows 10 but it'll have a watermark over every program in the bottom right corner. Only do this if the error check doesn't work. If it does it to the new HDD without the old one in your build at all then it could be an issue with your os if you simply transferred your license from your old computer to your new one. So in terms of troubleshooting for now. Update all drivers, run error checking on both Hard drives (which will take a couple hours to do the whole sweep of both and should actually fix the problem itself if it finds any problems, if the option appears to ask if you want that, you do). Lastly if these do not work, do a whole system wipe, remove your old HDD, leave just your new one, and reinstall everything including os. Just make sure you have a USB with windows on it to boot off of, there are tutorials to show you how if you need them. Good luck and let me know if this helps!
 
Feb 16, 2019
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Sorry, just read your post again. You said you kept your old HDD and got a new one for your OS. This could point to your old HDD as the issue since you say your old one did it too and this would be an HDD issue. Log onto your computer go to Start>my computer>{click on your old HDD storage drive}>properties>tools>{error checking} hit check. This will take a while but I honestly had the F1 to resume from S.M.A.R.T. status BAD until I did this the other day. If this does not help. Your HDD is bad. Could even be a possible virus in it so I would wipe everything including os, take out your old HDD, then reinstall your os on the one HDD you have in. Just make sure to get an 8gb minimum is drive and download the windows toolkit on it first so you can boot off of it. There's a lot of tutorials on how to do it and how to get your windows back so long as you have the key still. Or you can do free windows 10 but it'll have a watermark over every program in the bottom right corner. Only do this if the error check doesn't work. If it does it to the new HDD without the old one in your build at all then it could be an issue with your os if you simply transferred your license from your old computer to your new one. So in terms of troubleshooting for now. Update all drivers, run error checking on both Hard drives (which will take a couple hours to do the whole sweep of both and should actually fix the problem itself if it finds any problems, if the option appears to ask if you want that, you do). Lastly if these do not work, do a whole system wipe, remove your old HDD, leave just your new one, and reinstall everything including os. Just make sure you have a USB with windows on it to boot off of, there are tutorials to show you how if you need them. Good luck and let me know if this helps!
I only have it connected as storage. Also, for a period of time I disconnected the old HDD and the optical drive (another thing I saved from my old build) entirely, but the problem still persisted. In addition, I ran multiple scans on my current HDD and my old HDD using Seagate's diagnostic tools (both the HDDs are Seagate drives) and they both passed every single test I ran.

It's worth noting that since flashing my BIOS, things have been relatively stable. I had also been experiencing some audio issues with a new audio interface I bought recently, and those problems seem to have disappeared completely as well. I don't want to jinx it, but I would be overjoyed that it's fixed, but also a little upset if that was the issue this whole time lol. I just wish I checked for BIOS updates manually earlier; I was told that BIOS updates were covered by Win10 cumulative updates, but I guess that didn't happen. Not even my mobo's live update app was able to update thee BIOS after numerous attempts, so maybe Win10's updates weren't able to do it for similar reasons. Thank you all for your help and patience, I will report back should things go south (y)
 

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