Associate
Hi All,
As per the title my Asus X99-PRO doesn't keep its BIOS settings if I switch off at the PSU or the wall.
First up, it's not the battery at fault. I've replaced it with a brand-new, tested Panasonic battery and the result is the same, switch off at the PSU and everything resets - except the RTC.
If I go into BIOS after cutting the AC power, all settings are at base defaults but the clock always has the correct time and date. That's a fair indicator that it's not simply the battery, otherwise the RTC would reset too.
Intel's reference diagrams for the RTC/CMOS power circuit are very simple and it's easy to see how the battery should take over in the absence of AC power. Having looked at these I can't imagine a fault there as the RTC still works and VBATT indicates the battery is at a suitable voltage. If there was a failed decoupling capacitor or similar causing a ground short I'd expect the battery to discharge relatively quickly, but it doesn't.
This would all be more logical if the RTC reset along with the BIOS, then I'd be looking at either a failed decoupling capacitor or Schottky barrier diode (there's really not much else to fail here) and I'd tackle a repair myself.
I've seen loads of other posts on this subject and it's usually a straightforward case of battery replacement, this obviously isn't quite so simple however.
It's simply not worth RMA'ing it as it's out of warranty and I don't fancy my chances of receiving a reasonable repair bill and a board that's actually fixed, given how many negative experiences of Asus customer care I've seen. But, if anyone can point me to an actual fix, I'll be happy to make it worth their while as it's a donkey of a job going through all the settings each time I need to power off the system.
Or is this some undocumented feature that affects all Asus boards?
As per the title my Asus X99-PRO doesn't keep its BIOS settings if I switch off at the PSU or the wall.
First up, it's not the battery at fault. I've replaced it with a brand-new, tested Panasonic battery and the result is the same, switch off at the PSU and everything resets - except the RTC.
If I go into BIOS after cutting the AC power, all settings are at base defaults but the clock always has the correct time and date. That's a fair indicator that it's not simply the battery, otherwise the RTC would reset too.
Intel's reference diagrams for the RTC/CMOS power circuit are very simple and it's easy to see how the battery should take over in the absence of AC power. Having looked at these I can't imagine a fault there as the RTC still works and VBATT indicates the battery is at a suitable voltage. If there was a failed decoupling capacitor or similar causing a ground short I'd expect the battery to discharge relatively quickly, but it doesn't.
This would all be more logical if the RTC reset along with the BIOS, then I'd be looking at either a failed decoupling capacitor or Schottky barrier diode (there's really not much else to fail here) and I'd tackle a repair myself.
I've seen loads of other posts on this subject and it's usually a straightforward case of battery replacement, this obviously isn't quite so simple however.
It's simply not worth RMA'ing it as it's out of warranty and I don't fancy my chances of receiving a reasonable repair bill and a board that's actually fixed, given how many negative experiences of Asus customer care I've seen. But, if anyone can point me to an actual fix, I'll be happy to make it worth their while as it's a donkey of a job going through all the settings each time I need to power off the system.
Or is this some undocumented feature that affects all Asus boards?
