I recently found this thread as I'm also seeing the "CMOS checksum" error on restarts with my VGX-XL3.
I'm a little worried that this may be the first signs that my PSU may be on it's way out.
Curious if you were able to fix yours and if the CMOS checksum error disappeared? I've come to the same conclusion that it's not possible to reflash the BIOS (at least not without someone from a Sony repair center charging me an arm and a leg)
My advice is to replace the button cell battery ASAP (#CR2032) and clear the CMOS (reset BIOS). It's easy enough to do, and the battery replacement is probably due regardless Research I did suggested that to be at least a good possibility to resolve that issue. I wish I would have done that while I could instead of being lazy.
I've not resolved the PSU issue, and my Sony XL3 is sitting dead on the back burner and has been replaced with another HTPC....currently out of sight and out of mind. I'm actually hoping someone comes up with a PSU alternative in the near future and/or comes up with a 24/20-pin to Sony 18-pin mapping....hint...hint.
Hello Garret and Jack.
Garret, be sure to power-off, and disconnect the power cable from the back of the power supply before clearing the CMOS. It needs to be done without power to the motherboard. Even when the system is powered off, the power supply still provides standby power to the motherboard (evidenced by the lighted green standby power LED on the motherboard). This is why we always need to actually disconnect the power cord.
The CMOS unit is located close to the button-cell battery which Jack referenced. It is a 3-pin unit with the label "CLRTC" next to it on the motherboard. Only pin #1 is exposed (the other two pins, #2 and #3 are covered with a jumper). Move the jumper to pins #1 and #2, wait awhile and then move the jumper back to pins #2 and #3. This will reset to factory defaults. You can also clear the CMOS by disconnecting the power cord from the power supply and removing the CMOS button cell battery and not replacing it with the new replacement battery for awhile.
"Checksum error" can also be caused by any program in your startup directory which uses a checksum program or MD5 hash checker; or in rare circumstances can be caused by a virus. If replacing the CMOS' button-cell battery and clearing the CMOS does not correct the problem, you might then next want to disable programs running at startup:
The System Configuration Utility, or MSCONFIG, will show you all the programs running at start-up, even ones that are hidden. Click "Start", then "Run" and then type "msconfig" in the box, then click "OK".
- When the System Configuration Utility window opens, click the "Startup" tab. A list of all start-up programs available will be seen, with checkmarks showing which ones are enabled. Uncheck the boxes for all startup programs you wish to disable, starting with any programs you may have installed around the time you began noticing the "Checksum error" messages. If you're not sure which of these programs you may want to keep enabled at startup, disabling them is reversible. You can always recheck the boxes.
- When Windows starts again, you will see a screen reminding you that the startup program has been altered. Check OK to get rid of that prompt.
Lastly, if "Checksum error" is caused by a virus or other Malware, you can sometimes rid the system of malware not found by your antivirus / antimalware utility during normal usage, by booting the computer in "Safe mode" and then running your antivirus / antimalware application(s).
Malwarebytes has a 15-day free trial download which you can grab from FileHippo.com My experience has been that Malwarebytes is especially effective finding pesky hidden malware, when running a scan in Safe mode. Let us know if any of these suggestions yields a fix for the "Checksum error.".
PS. Jack, I haven't forgotten you. I just ordered a new multimeter with leads small enough to test the 18-pin molex connector. I'm still looking for that pin-out, but "Plan B" is now afoot and I'm ready for the trial & error method, ...and I will not stopped!
Edited by REnninga - 3/7/13 at 9:34pm