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So, this is another thread asking for help, ideas, cheese and/or an infinite supply of fish sticks and mayonnaise.
TL;DR version in bold letters at the end.

I've received my new motherboard that should allow for not only a cooler and more stable system, but also for AMD's ACC featurette. The board in question is Gigabyte's MA790X-UD3P.
This will also be my ticket to AM3-CPU-upgrade-land, where I won't need ACC anymore.

But for now, I'd like to know exactly what's going on.

I have an unexplained menu inside the BIOS, a choice of two different "firmware versions" (normal and hybrid, "EC Firmware"), and enough unexplained percentages thrown around to make an accountant's head hurt.
I can change the percentage value one core at a time, or uniformly for all of them, or I can just set it to "auto".

No matter what I do, it actually just merely lowers the stability of the motherboard, greatly reducing the chance of a successful POST even at astonishingly mild overclocks (or sometimes no overclock whatsoever).
There's no explanation in the manual, online, or anywhere else.

So,
Does someone know what the hell those percentages change in a core (ranging from -12% to +12% in my case), and how it's supposed to help? All this time I've been thinking I'll just throw a switch and I'll arrive in candyland. I guess AMD had other plans.
With that said, I don't complain because the board can take higher reference clocks than the old one, but it's a pity that processor-assisted virtualisation renders the operating system unloadable (at least in overclocked conditions). I've decided not to care because I almost never use my VMWare. The important thing is that I have a good board with AM3 and Crossfire capability, if I ever decide to burn my 8800 GT, that is.

But still,
How am I supposed to correctly use ACC?
What do the percentages stand for?
Why does it actually decrease my stability?
Is there a source where someone (preferably AMD) explain all this humbug?

Thanks

http://lmgtfy.com/?q=Advanced+Clock+Cal ... n+settings
I'd just set it to auto.
Rumor is that it could be related to skew, but nobody knows for sure.
I've also heard that Phenom II's don't need it.
Who knows.

l33t-g4m3r wrote:

http://lmgtfy.com/?q=Advanced+Clock+Calibration+settings
I'd just set it to auto.
Rumor is that it could be related to skew, but nobody knows for sure.
I've also heard that Phenom II's don't need it.
Who knows.

That wasn't helpful at all, I'll keep it turned off then.

Auto is probably the best setting to leave it on if you want to enable it. What I've seen most overclocking guides say is to enable ACC once you've reached the limit of your overclock without it on. You first try it on Auto and see if that increases your headroom. If it does, great, keep overclocking. If it doesn't, you can see if you can figure out which core is failing specifically when you push past the limit and then adjust the ACC percentage for that core (I can't remember if it's up or down, but you're supposed to try both). You can do this all in conjunction with raising the vCore to try and dial in the maximum stable overclock. From what I've been able to gather, ACC has an effect on how lax a core can be with regards to the timing of electric signals. Of course, all this was just gathered from several weeks of Googling and trawling through the tubes so I can't vouch for its validity. AMD for some reason doesn't release much technical information about ACC other than it's supposed to make overclocking easier and let you reach higher overclocks. I haven't been able to test ACC ever, since enabling it prevents me from even POSTing on my motherboard, which is another issue entirely.

Zoomastigophora wrote:

I haven't been able to test ACC ever, since enabling it prevents me from even POSTing on my motherboard, which is another issue entirely.

This last sentence invalidates your comment altogether, not to mention I have the same issue and have difficulty POSTing when ACC is enabled in any form.
I've also googled up a bunch of other people observing the same.
I wondered if anyone knew why that is.

Well, my 2 cents...

The "hybrid" firmware mode is what allows you to potentially "unlock" disabled cores in the event that your CPU has any.

This is mentioned here: http://techreport.com/discussions.x/17037

It worked for me with Phenom II X3 and Gigabyte motherboard listed for this season's Econobox, and though I haven't stress-tested it too badly, I now have 4 cores instead of 3.

If you are enabling "hybrid" mode, perhaps you're unknowingly activating an unstable core? You never mention what CPU you're using.

I have it set to auto. Can't OC past 3.2 on my 940 though.
Haven't tried with it off, but I don't really need the extra Mhz.
It could just be a feature for the older am2+ boards/CPUs.
I swear I read somewhere that it's automatic on the newer chips. Could be wrong.

Agree with Arxor on the hybrid mode, that's probably all you need bios ACC for, if the am3 cpu's have it on internally.

Arxor wrote:

If you are enabling "hybrid" mode, perhaps you're unknowingly activating an unstable core? You never mention what CPU you're using.

That would be exciting, because I'm using a Phenom X4 9550 processor.

l33t-g4m3r wrote:

I have it set to auto. Can't OC past 3.2 on my 940 though.

It's not supposed to do anything to any of the processors marked with that Roman number two.

Meadows wrote:

l33t-g4m3r wrote:

I have it set to auto. Can't OC past 3.2 on my 940 though.

It's not supposed to do anything to any of the processors marked with that Roman number two.

supposedly.
Or maybe it bypasses automatic mode, for manual.
Either way it doesn't really do anything for me.

Meadows wrote:

This last sentence invalidates your comment altogether, not to mention I have the same issue and have difficulty POSTing when ACC is enabled in any form.
I've also googled up a bunch of other people observing the same.
I wondered if anyone knew why that is.

About the only trend I see with ACC causing no POST with the M3A79-T Deluxe (my motherboard) is that the people with the issues all have a 1000W PSU. And I was only offering the information that I managed to gather over several weeks worth of Googling so that you could avoid having to do the same and arrive at what I did, but since I haven't used ACC successfully, my research clearly doesn't matter so I'll be sure to never try offering information in any thread you create anymore.

Zoomastigophora wrote:

About the only trend I see with ACC causing no POST with the M3A79-T Deluxe (my motherboard) is that the people with the issues all have a 1000W PSU. And I was only offering the information that I managed to gather over several weeks worth of Googling so that you could avoid having to do the same and arrive at what I did, but since I haven't used ACC successfully, my research clearly doesn't matter so I'll be sure to never try offering information in any thread you create anymore.

I've arrived at similar conclusions after 30 minutes of binging for some know-how, except that I myself use a different motherboard and a not-so-recent, 550 W power supply.
How's that for consistency?

Edit: ACC is dead then, at least it makes me want that Athlon II X4 replacement a bit more. It's a good thing that feature wasn't the only reason for getting the new board.