We've seen that every board acts differently when it comes to LLC. You did the right thing by experimenting with it a bit. Even different boards by the same manufacturer act different.
You're right though that just seem ludicrous to me!
You wrote what is about as accurate as can be written. "Storm-Chaser" took issue when I linked an FX cpu discussion of what CPU_LLC would likely cause when used on these cheaper boards with only 3 choices for CPU_LLC. AUTO > DISABLE > ENABLE. That particular user I gave the link to, had a Deneb processor and not FX. However to my mind any discussion of CPU_LLC is relevant to the situations we face today and how odd CPU_LLC can work even on the same brand and model of motherboard but for a different user with a different mobo.
"S-C" did say that I likely could do this stuff 'blind-folded' and that was sort of true. I can do it but I need to see the keyboard to enter the stuff and also to see the captures the users have of HWMonitor. To try and get to the bottom of LLC on AMD motherboards we must go back in history a bit.
Before the release of the FX processor there was NO Vdroop as a specification set forth by AMD. Nada. Zip. A very prominent Vdroop specification came with the release of the FX series of processors. That is why in early bioses used for Deneb and Thuban processors on 9xx chipset boards the CPU_LLC choices for Enabled said for FX processor only in the right hand pane of most early motherboard bioses on 9xx chipset boards using non-FX processor. Heck we had 9xx chipset boards in the market nearly a year before AMD release the first pig of an FX processor.
So the bios writers hid for most who did not look in the right pane that LLC should be off/disabled unless the processor in the socket was an FX processor. This is why "iueras" has better luck with his 955BE in the socket and CPU_LLC actually disabled and the bios voltage set to a voltage that is passing P95 Blend. Heck CPU_LLC Disabled is actually running his pre-FX cpu in the manner it was designed and all the Pre-9xx boards did operate.
Now comes some more of the story. When I tested an Asrock Fatal1ty 990FX motherboard, I found that the Asrock CPU_LLC worked just backwards to what I was accustomed to seeing on my Asus CHV motherboard. I want to state right here that once I understood that the PRIMO Fatal1ty mobo CPU_LLC was working backwards and responded accordingly...well it worked just FINE. I just had to understand that Asrock CPU_LLC called into use at a lesser amount of LLC equaled what calling "more" LLC into use did on the CHV. That is about as 180 degrees from being the same as you can get. However the knowing of how the bios writers interpretted CPU_LLC to function was the key to using either the Asus board or the Asrock board. Sadly the cheaper Asus and Asrock and Gigabyte motherboards do not have a CPU_LLC that can be 'fine-tuned' for use.
So where does all of that really leave us?
1. CPU_LLC is a spec and design parameter for FX processors and not Pre-FX processors.
2. Some cheaper boards with CPU_LLC on them will often work okay with a Pre-FX processor. Some will not and DISABLING CPU_LLC on those boards is to actually run that Pre-FX processor as it was originally designed to be operated. Set manually a Vcore that will allow the non-FX processor to pass P95 Blend and the "loaded" voltage will tend to rise over the voltage set in the bios. That was the way most Denebs ran on earlier chipset motherboards.
3. On the really good boards such as the CHV and Sabertooth and the Asrock Fatal1ty 990FX boards and likely just a few others of the upper echelon AMD 9xx boards, there is a much finer CPU_LLC circuit on the motherboard. This extra adjustability of the more robust motherboards, can likely allow for the 'better/easier' use of CPU_LLC on the Pre-FX processor.
I know this to be true for a C2 stepping 955BE which is not even the better C3 that everyone wants. I used CPU_LLC to get the cpu Vcore correct and run that old C2 955BE at 3.9Ghz P95 Blend stable without undue temps or Vcore. The same was also doable on the Asrock Fatal1ty motherboard I used for a while. Just had to remember the CPU_LLC was operating backwards from the CHV by Asus.
4. So I expect the truth of the matter is that most users with Pre-FX processors might do well to run with CPU_LLC disabled on 9xx chipset motherboards, simply because the Vcroop spec which CPU_LLC is trying to counter-act was not enacted until the FX processor came on the scene. However if the cheaper brand board, no matter the brand can be sorted to run CPU_LLC, then sure use it. But the settting of CPU_LLC is going to be a 'per-user' setting that ONLY trial and error at the keyboard of each system can determine the actual outcome.
Most of this only comes after hours and hours of digging and searching. Seeing early bios screenshots of the early bioses on AMD 9xx chipset boards before later and later bioses were released, to have seen that disclaimer about LLC for non-FX processors. I mean it has been months since this question of CPU_LLC oddity has come up on a Deneb processor installed in a cheaper 9xx chipset motherboard.
H*ll my memory is not what it used to be. I had written most of this down in my "AMD Cpu Notes" or I might not even remember the time-line as it has unfolded. I just had never taken the time to put this in a post since CPU_LLC equal OFF is the setting to use if the cheaper board acts a fool with CPU_LLC on and a non-FX processor is in the cpu socket.
This was not intended to speak to the use of CPU_LLC on better boards with an FX processor in use, but only to give a little insight as to a reason the Pre-FX processor may well be easier to manipulate for stability if CPU_LLC was in fact DISabled. AS in anything computer related, it seems the standard YMMV applies.
RGone...