Question about Haswell Voltage

[Galatian]

Hi everybody,

I'm not sure if this has been asked before, but I haven't followed all the posts about the original Haswell release and now that I have a Devil Canyon I'm trying to figure out how the voltage is regulated:

Is it correct that Haswell does not provide a fixed voltage anymore, meaning you can't set a voltage that will always be on?

It seems like Haswell only provides a override voltage, where one can set a maximum voltage that is applied at load?

What exactly is the difference then in using adaptive voltage? Is it only there to provide the few mV more need for FMA3 and AVX2 loads?

I hope a few people can answer me those questions. Haswell voltages are totally different from Ivy and Sandy and a little bit counter intuitiv. Trying to wrap my head around that topic.

 

[rallycobra]

I need help with this too! I have a Gigabyte Z87 board and was getting 1.4 cpu vcore and 100C temps with optimized bios defaults. Crazy!

I locked the cpu core at 1.25 and cpu cache at 1.1 and now my temps are only 75 on the Intel Extreme Tuning Utility Stress Test. If someone comes up with settings for adaptive voltages, I would love to know them. Otherwise, I will keep using static voltages.

 

[BSim500]

Is it correct that Haswell does not provide a fixed voltage anymore, meaning you can't set a voltage that will always be on?

It seems like Haswell only provides a override voltage, where one can set a maximum voltage that is applied at load?

From what I understand (I still have an Ivy Bridge myself):-

- Haswell's "feature" of arbitrarily adding +0.10-0.15v on AVX loads are what primarily drives temps through the roof on synthetic "burn" tests.
- Haswell's FIVR makes precision voltage control more difficult and motherboard dependent anyway compared to previous generations.
- "Fixed" is typically "fixed" for load but some motherboards (Gigabyte) will still undervolt on idle, whilst others won't (Asus?). It usually does override the auto +100mv AVX thing.
- "Offset" will offset both idle & load same amount (as Ivy, etc). It may or may not override the auto +100mv AVX thing.
- "Adaptive" will offset only load voltage. It usually doesn't override the auto +100mv AVX thing.

Or something like that...

 

[JimmiG]

You should have the option to either set a fixed voltage or use offset/adaptive. With the offset or adaptive setting, you'll get the VCore boost when running AVX/2 stress tests.

Unless you actually use any AVX applications, I think adaptive works best, since you're guaranteed a low idle voltage - saves power, keeps idle temps lower and potentially increases the life span of the CPU.

 

[Techhog]

From what I understand (I still have an Ivy Bridge myself):-

- Haswell's "feature" of arbitrarily adding +0.10-0.15v on AVX loads are what primarily drives temps through the roof on synthetic "burn" tests.
- Haswell's FIVR makes precision voltage control more difficult and motherboard dependent anyway compared to previous generations.
- "Fixed" is typically "fixed" for load but some motherboards (Gigabyte) will still undervolt on idle, whilst others won't (Asus?). It usually does override the auto +100mv AVX thing.
- "Offset" will offset both idle & load same amount (as Ivy, etc). It may or may not override the auto +100mv AVX thing.
- "Adaptive" will offset only load voltage. It usually doesn't override the auto +100mv AVX thing.

Or something like that...

I've heard that the consensus is that it's actually less motherboard dependent. Then again, I always get mixed messages on this forum. :/