Bitlocker or Encryption Process Caused Crash/Shutdown?

I decided to encrypt a 8TB external hard drive that already had about 3.5TB of data on it....mistake. After initialization, the encryption process crashed my computer three times (computer simply shut off). After a few hours, and seeing it was only 1% done, and because I had the data elsewhere, I gave up and reformatted the drive and decided to encrypt it while empty. So far so good....re-copying data back to it. I formatted it exFAT instead of NTFS and am copying at between 150 and 200 MB/s. Hopefully it doesn't crash any more.

How do you know that it was specifically BitLocker that crashed the computer? I find that EXTREMELY unlikely. Could it have been something else underlying that caused the problem? For example, the process of performing BitLocker encryption necessarily puts a lot of stress of systems such as reading and writing large amounts of data. Is it possible that doing similar operations outside of BitLocker would have caused the shutdown?

Also, a shutdown seems odd for a crash. Normally with a crash you would expect a reboot.

Is there anything in the event logs that indicates what happened?

One more question, simply out of curiosity: Why did you decide to go with exFAT rather than NTFS? To my mind, that's simply stripping you of a lot of capabilities.

You're probably right that it might not have been Bitlocker itself but the encryption/decryption process itself for that amount of data. After the three failures drive was only at 1% which is why I gave up. Event Viewer is vague...just Error 41 KERNEL-POWER (The system has rebooted without cleanly shutting down first. This error could be caused if the system stopped responding, crashed, or lost power unexpectedly). However, I have copied large amounts of data before and never had anything like this happen.

As for why exFAT...normally I use NTFS like you said. However, and I'd appreciate your opinion as you seem to have knowledge on the subject, I opted for exFAT really to try it out. I read online (admittedly it is always fine to question sources) that in addition to being more compatible (Mac, Android streaming boxes, etc.) it is faster on USB connection than NTFS...without the old limitations of FAT32. Thanks to your post, I just found some tests that says otherwise. Since I haven't copied that much data back on it yet, I may opt to set it back to NTFS....the Bitlocker encryption might make the compatibility advantage painful anyways...it looks like you'd need 3rd party software on another system anyways to unlock it.

I agree with the other guy, that Bitlocker isn't the problem, and you should continue using NTFS. Have you run a program like CrystalDiskInfo to inspect the SMART values for the drive? Even if the drive is failing, it shouldn't cause a spontaneous reboot, but it would still be good to know. Since it happened three times, something else involved in the procedure would seem to be failing. Could be a bad USB port or cable. For example, the Antec P180 case failed to ground its front USB ports, and if you weren't supremely skilled at inserting the cursed things, the system could reboot when you plugged one in. Your problem isn't like that, but I suppose it could manifest over time. I'd expect any comparably lengthy operation involving continuous read/write to result in the same behavior as with Bitlocker. The encryption shouldn't be a major hit to CPU usage, even with old CPUs lacking the AES extensions, so I doubt it's anything like a heavily used CPU drawing too much power from a failing PSU. That's something you could test with a program like Prime95, which is probably a good idea to try anyway. It can ferret out failing memory, as well.

Thanks to both of you...and in the process of setting the drive back to NTFS now...fortunately I hadn't put a huge amount of data back on it. It actually looks like more products (i.e. routers and NAS enclosures are compatible with NTFS too) I haven't had any other issues with computer shutting down including copying 1TB of data since that initial encryption attempt...and never had any issues before. It is definitely possible it was a USB malfunction. Twice it failed when plugged into a hub, and the third time was plugged into the front port of the tower itself (a Phanteks Eclipse P400 I think). No blue screen or anything either...it simply shut off. All of my drives passed health-wise and, you're right, while the encryption process was going to be EXTREMELY slow, CPU and Memory usage remained low...weird.