[mdlug] 2 very different gigabyte motherboards not keeping good time

[Adam Tauno Williams]

On Mon, 2014-04-14 at 22:32 -0400, Dan Pritts wrote:
> For several years I’ve run an old 1.9GHz 64-bit athlon, with a gigabyte motherboard.  
> It never kept good time, whether running under freeBSD (8.x then 9.x) or linux (centos6).  
> NTP couldn’t keep it synced, 

In 25 years as a sys-admin I've never met a box that NTP couldn't keep
in sync - at least not one where the settings weren't completely
wrong.  

The clock drifts significantly WHILE-THE-BOX-IS-RUNNING *OR* is totally
kitty-whumpus AFTER-RESTART/BOOT?

> I recently upgraded the system to a “pentium” haswell chip. 
> Guess what, it doesn’t keep time, and NTP can’t keep up.

And what components did you retain between the two systems?  Video card?
Some other device?  

You have a daisy chained mess of USB devices hanging off the box which
resembles a rail switching yard?

You diddle with the kernel or set some unusual boot-string options
regarding APIC or ACPI?

> I do not have the system on a UPS or anything else that might muck with 
> the power frequency coming in.  Just plugged in to the wall, 
> DTE power in the middle of ann arbor.

There is no circuit which references the 'socket clock' in a modern box.
Otherwise how would a laptop keep time?  If your system has an Intel
chipset the RTC is contained in the Southbridge.  The Southbridge
handles all the `low speed` and `legacy` devices - creating an avenue
whereby it is at least theoretically possible for these devices to
disturb the operation of the RTC.

> Any thoughts on what could be causing this?  I’m left with two thoughts, 
> PSU or just crappy gigabyte timekeeping.  
> PSU seems unlikely - the system has otherwise been very stable.

Agree.  No way a name-brand mobo exhibits this behavior, and not across
two distinct chip-sets.

>  bad gigabyte time also seems unlikely, but what do i know. 

There is a hidden-actor in your story;  one you are too accustomed to to
take notice of.

-- 
Adam Tauno Williams <mailto:awilliam at whitemice.org> GPG D95ED383
Systems Administrator, Python Developer, LPI / NCLA