Optiplex 755 USFF will not boot after changing cmos battery

Hi kmcstech,

Perhaps you are new to computers, but when you replace the CMOS battery, you need to boot directly into the BIOS and restore the settings you had before you swapped the battery.

There are two settings you likely need to fix based on that blue screen error. First, find the section of the BIOS called SATA operation. The default is AHCI. You probably need to change this to ATA.

Second, find the drives list, and make sure both SATA 0 and 1 are ON.

Then see if the system will boot.

My error was not writing down the settings in BIOS before replacing the battery. I felt resetting to default settings was a safe bet.

After replacing the battery, it immediately stopped with a message that date & time needed to be set along with system management. Press F1 to continue or F2 go run setup. I pressed F2, entered the date and time, saved the settings and exited. Upon re-boot is when the loop - reboot occurs.

I changed the SATA operation from AHCI to ATA. Second I checked that SATA 0 was set to on. There isn't a SATA 1. I saved the setting and re-booted. I have the same problem, nothing changed. Booting regularly from the hard drive gives the "start windows" options of safe mode, safe mode with networking, safe mode command prompt, last know good configuration and start normally. All of the options will display the WIndows XP start screen with the blue dots going across the bottom and once they go across the computer will re-boot.

I've tried the re-boot with 3 different hard drives, different makes but all 80 GB at 7200 rpm. None of them work in the 755 Optiplex but they all work in an Optiplex GX280.

Any other suggestions as to what I can try?

I wouldn't just swap drives into the system willy nilly. You need to try to boot with the drive loaded with the OS for this system.

At this point, you're going to need to perform a repair install. For that, you'll need to boot to your Dell XP disc.

All of the hard drives I've swapped are of the same size and speed as the original drive. All of them have Windows XP service pack 3 on them. In trying to determine if the original hard drive failed I swapped it into another Dell computer and it boots just fine. There I concluded that the problem is not the hard drive.  Clearly there is a setting in BIOS not set correctly.

In my original post for help I explained that I can't do a repair install or any install for that matter. Here's what I posted and happens when trying to install:

I've tried to reinstall the OS and get all the way to "starting windows" and then the blue screen of death stop error 0x0000007B (0xF7A10524, 0xC0000034, 0x00000000, 0x00000000).

As long as the controller mode is set to ATA, that 0x7B error should not be happening. Unless, that is, there's a problem with the drive itself or the boot sector. Given that you've tried three drives, I think one of them has got to be good. So that leaves the boot sector. Are you deleting ALL existing partitions when you start the installation process?

Excellent! Glad that worked. Thanks for posting back.

Just for edification, I had a an Optiplex 760 with the same problem after changing the CMOS battery (same error, BSOD, etc.)  I was panicked because I had just re-installed the OS after an HDD change and done ALL the updates.  The scary part is that Windows kept wanting to go into recovery mode.  Who'd a thunk it was the BIOS?!  I'm not even sure the 755 and 760 have the same or similar mobo's, but AHCI to ATA did the trick. Thank you, Osprey!

Thanks for your post on correct BIOS settings..

Thank you for this posting.  It saved me some hair pulling-out for sure.  It worked for me as well, same system, Dell 755

Thank you so much for posting this. I have no clue about computers at all but w/research I was able to locate my battery, change it, then figure out why it just wanted to keep rebooting, and fix that problem. Before today I had never even taken the cover off my tower (I had to look up how to do that as well). I'm feeling quite accomplished right now, and you helped w/that in a big way. Thank you for following up and giving so many of us the solution to the problem.  :emotion-2:

To all here - I am NOT a computer tech but I noticed the advice here to change your BIOS from AHCI to ATA.  (And Osprey always has good advice.)

Well, the following Microsoft article MIGHT (maybe) let you leave the BIOS SATA Operation setting in AHCI - although I am NOT sure.  It has worked for me on two Optiplexes.

See http://support.microsoft.com/kb/922976.

Personally, I did NOT run the Mr. Fixit in that article.  Instead, I followed the regedit instructions, which were easy.

But before doing this, you should get familiar with booting up into your BIOS so that you can change back to ATA if you still have a problem.

I no this was a long time ago but it worked for me and no-one happier

Thanks everyone who provided feedback and suggestions

That's how we get on in life by helping those in need

\\Shooter

Thank you for this! Saved my Optiplex too!! :)