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Help me understand LLC? - Page 2

post #11 of 23
Thread Starter 
Quote:
Originally Posted by Gunderman456 View Post

How best to describe... It's like a teeter-totter, you can lower vcore/offset and go higher on LLC or vise versa, as you want your vcore to be at its truest.

actually a great analogy. I need 1.5v to run at 4.2ghz. so, should I set it to, say 1.45 with a higher LLC? Or 1.5v like I have, and a low LLC (6%)
post #12 of 23
You will need to input the numbers in Bios, open CPU-Z and stress the CPU with Prime95, observe vcore volts and adjust as needed.
 
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post #13 of 23
I would personally set a lower voltage and higher LLC, mainly so its not constantly inputting 1.5 volts through to your CPU regardless of CPU state. It would drop to 1.45 now and again, so should help with CPU life and heat slightly.

At idle and power saving options enabled a lower vcore is always better than a higher vcore.
post #14 of 23
Thread Starter 
Quote:
Originally Posted by mikeo01 View Post

I would personally set a lower voltage and higher LLC, mainly so its not constantly inputting 1.5 volts through to your CPU regardless of CPU state. It would drop to 1.45 now and again, so should help with CPU life and heat slightly.
At idle and power saving options enabled a lower vcore is always better than a higher vcore.

Only under load is it 1.5v, I have cnq enabled, so its under 1.2v 90% of the time. But, Ill look into it.
post #15 of 23
VID is the voltage identification of the processor. It means how much the processor is telling the bios it needs to run at its official frequency per AMD's specification. Each processor, even of the same model and stepping can have a different VID. This is because each processor is different. The VID of a CPU can give a hint to whether the CPU is a low leakage or high leakage part, which also gives a clue to how well the CPU will overclock on air or sub zero cooling and a hint to how hot the processor will run. Each pstate will also have its own VID. So you dont set the VID of the processor in the bios, it is part of the processor.


higher VID denotes lower leakage, lower VID means higher leakage. higher VID = better for air cooling, lower VID = better for LN2 clocking. The batch matters too, it is possible for a great batch'ed lower VID to beat a sucky batch with a higher VID

Lets take this example with a Phenom 965:
965 TDP = 125w
if VID is 1.4v then heat dissipation is 125w maximum
now if the VID is 1.3v, then max TDP is still 125w

the voltage is lower on the 2nd chip because it would exceed its TDP with higher voltage, this means more leakage. There is more too it, but this is a good basic understanding.



VID is not the same as vcore.
vcore is the amount of voltage being sent to the processor cores. This is what you set in the bios.You can raise the vcore to send more voltage to the core so you can run higher clock speeds, but too much voltage will kill the processor, or damage it, or lower its lifespan. For a Phenom II 965 I wouldnt send more than 1.55v MAX to the processor, which means you should keep the vcore around 1.5v or lower to be safe. This allows for small spikes from LLC to not damage the CPU.



Now as for LLC, or load-line calibration. You should NOT set a really high LLC because this can cause a massive spike in voltage when the processor changes from load to idle. This is because the voltage is being boosted by so much to compensate for vdroop and when the processor stops being loaded it still has that massive voltage boost for a short time before the LLC reacts and stops sending voltage. You can see spikes of over 1.7v to the CPU when running high LLC, which is way more than a CPU should get and can damage or kill the processor.

Personally I would never EVER go above 50% LLC, and usually I stick to 25%. My motherboard only has 0, 25, 50, etc and cannot set values like 6%
Edited by EniGma1987 - 10/31/12 at 9:25am
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post #16 of 23
Good description EniGma1987 smile.gif

A lower VID is better because it requires less voltage to be stable, whereas if VID is at 1.4 you have little room to play around with and probably means the die requires more voltage to run.
Yeah vcore is the amount sent to the processor, the VRMs manages this, that's what I meant by actual voltage.

LLC compensates for vdroop. A higher LLC doesn't necessarily mean a spike in voltage.For instance, my board LLC at 100% gets the voltage as close to the set CPU voltage as possible.

If my CPU voltage is set to 1.4, and my LLC is on "Extreme" (100%) I will probably see 1.428-1.45 in voltage spikes.

It depends on the board and the chip, as long as LLC is set to the amount of vdroop your fine. Same if you provide more voltage to the chip through LLC. LLC will only provide more power to what you set.

If you have cool and quiet enabled then leaving it at 1.5 is fine because it'll only hit that voltage upon load. I vary, right now I have 1.4125 for my CPU and LLC to 75%, so my vcore stays at 1.412-1.43. It doesn't spike, it just provides extra juice. When my CPU is idle its at 1.4125, otherwise my idle state would be at 1.43 which is unnecessary.

The overclock is up to you, and up to you how you manage it, as long as voltages and temperatures are in the save range your fine. The VRMs only provide power on what you tell it too. As long as its stable and isn't running at 1.5 constantly its fine.
post #17 of 23
Thread Starter 
Quote:
Originally Posted by EniGma1987 View Post

VID is the voltage identification of the processor. It means how much the processor is telling the bios it needs to run at its official frequency per AMD's specification. Each processor, even of the same model and stepping can have a different VID. This is because each processor is different. The VID of a CPU can give a hint to whether the CPU is a low leakage or high leakage part, which also gives a clue to how well the CPU will overclock on air or sub zero cooling and a hint to how hot the processor will run. Each pstate will also have its own VID. So you dont set the VID of the processor in the bios, it is part of the processor.
higher VID denotes lower leakage, lower VID means higher leakage. higher VID = better for air cooling, lower VID = better for LN2 clocking. The batch matters too, it is possible for a great batch'ed lower VID to beat a sucky batch with a higher VID
Lets take this example with a Phenom 965:
965 TDP = 125w
if VID is 1.4v then heat dissipation is 125w maximum
now if the VID is 1.3v, then max TDP is still 125w
the voltage is lower on the 2nd chip because it would exceed its TDP with higher voltage, this means more leakage. There is more too it, but this is a good basic understanding.
VID is not the same as vcore.
vcore is the amount of voltage being sent to the processor cores. This is what you set in the bios.You can raise the vcore to send more voltage to the core so you can run higher clock speeds, but too much voltage will kill the processor, or damage it, or lower its lifespan. For a Phenom II 965 I wouldnt send more than 1.55v MAX to the processor, which means you should keep the vcore around 1.5v or lower to be safe. This allows for small spikes from LLC to not damage the CPU.
Now as for LLC, or load-line calibration. You should NOT set a really high LLC because this can cause a massive spike in voltage when the processor changes from load to idle. This is because the voltage is being boosted by so much to compensate for vdroop and when the processor stops being loaded it still has that massive voltage boost for a short time before the LLC reacts and stops sending voltage. You can see spikes of over 1.7v to the CPU when running high LLC, which is way more than a CPU should get and can damage or kill the processor.
Personally I would never EVER go above 50% LLC, and usually I stick to 25%. My motherboard only has 0, 25, 50, etc and cannot set values like 6%

this helped me a lot, thank you. I was curiousthe difference between VID and the actual vcore. CoreTemp tells me my VID is 1.45v, and Im running it at 1.5v, with spikes for a half second, and rarely, at 1.536v. The highest is usually 1.52 or just 1.504. I have CnQ enabled regardless, so my vcore drops to 1.2v at idle (230 x4)
post #18 of 23
Thread Starter 
Quote:
Originally Posted by mikeo01 View Post

Good description EniGma1987 smile.gif
A lower VID is better because it requires less voltage to be stable, whereas if VID is at 1.4 you have little room to play around with and probably means the die requires more voltage to run.
Yeah vcore is the amount sent to the processor, the VRMs manages this, that's what I meant by actual voltage.
LLC compensates for vdroop. A higher LLC doesn't necessarily mean a spike in voltage.For instance, my board LLC at 100% gets the voltage as close to the set CPU voltage as possible.
If my CPU voltage is set to 1.4, and my LLC is on "Extreme" (100%) I will probably see 1.428-1.45 in voltage spikes.
It depends on the board and the chip, as long as LLC is set to the amount of vdroop your fine. Same if you provide more voltage to the chip through LLC. LLC will only provide more power to what you set.
If you have cool and quiet enabled then leaving it at 1.5 is fine because it'll only hit that voltage upon load. I vary, right now I have 1.4125 for my CPU and LLC to 75%, so my vcore stays at 1.412-1.43. It doesn't spike, it just provides extra juice. When my CPU is idle its at 1.4125, otherwise my idle state would be at 1.43 which is unnecessary.
The overclock is up to you, and up to you how you manage it, as long as voltages and temperatures are in the save range your fine. The VRMs only provide power on what you tell it too. As long as its stable and isn't running at 1.5 constantly its fine.

Also, not sure if it is CnQ (possibly) but something strange happens. SInce I enabled it, and only when it is, under load my BUS speed decreases. I know CnQ lowers the multiplier, but my buss speeds drop from 230 to 227, 220, all the way down to 100 sometimes under a blend test....***?
post #19 of 23
Well, my only thought on dropping bus speeds is that maybe this is how throttling works? I always thought the CPU multiplier was dropped when a processor begins throttling but I suppose a bus speed drop is also possible. The bus speed drop would mean that the base speed is being lowered so all frequencies would be affected. However, what you describe seems unlikely since I have never seen a system able to boot when the bus speed is set too low, the lowest I have been able to try was 170 (default of 200). Cool N Quiet turned on will definitely enable throttling with high temperatures, so maybe this is what is happening. You could try turning off all energy saving things and see if this behavior still happens.

Also, what are your load temps? After say 10 minutes of a Prime95 large-FFT run?
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post #20 of 23
Thread Starter 
Quote:
Originally Posted by EniGma1987 View Post

Well, my only thought on dropping bus speeds is that maybe this is how throttling works? I always thought the CPU multiplier was dropped when a processor begins throttling but I suppose a bus speed drop is also possible. The bus speed drop would mean that the base speed is being lowered so all frequencies would be affected. However, what you describe seems unlikely since I have never seen a system able to boot when the bus speed is set too low, the lowest I have been able to try was 170 (default of 200). Cool N Quiet turned on will definitely enable throttling with high temperatures, so maybe this is what is happening. You could try turning off all energy saving things and see if this behavior still happens.
Also, what are your load temps? After say 10 minutes of a Prime95 large-FFT run?

I thought small FTT was more intensive. After an hour of Large FTT i get no higher than 52 (for a split second, then goes down to 51)* centigrade. The voltage is at 1.5, but goes to 1.52v and ocasinally spikes to 1.536 for a second. I have a little bit of head room, but Im sticking to my 4140mhz clock, its a GREAT overclock and im going to see no difference out of another 60mhz...which I cannot get stable anyways, i refuse to set the vcore over 1.5 in the bios.
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