- Mar 8, 2008
- 9
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- 18,510
I want to overclock but not at all interested in running close to my max voltage for the CPU. Here is where the problem lies, getting the facts clear as to what value constitutes the max CPU voltage (Vcc) for my chip.
The E8400 box showed the following:
Batch: Q745A740
sSpec: SLAPL
Version: E27439-001
Pack Date: 01/21/2008
1.225V Max
The '1.225V max' - Is this the Vid rating for my particular chip? If so, then is CoreTemp ver 0.97.1 displaying the wrong Vid of '1.1125v'. My BIOS default auto settings give a Vcore of 1.225v (coincidence or reading the Vid from the BIOS at boot and adjusting to suit?).
The Intel datasheets have some complicated way of trying to give the max Vcc. First off they say Vcc absolute max is 1.45v but this, quote 'lies outside the functional limits of the processor'. So what is the functional limits... I read on. Vid range set at manufacture time can be between 0.85 and 1.3625v. Vcc min and max are differences from Vid (depending on current draw) as shown in a graph.
Then, if I read the graph right, at 0A Icc, Vcc max = Vid. At max Icc (75A - wow!), Vcc max = Vid - 0.105.
So, if my Vid is 1.225v (as maybe shown on the box), then my Vcc max at max load is 1.12v.
And if I believe CoreTemp's Vid of 1.1125v, then my Vcc max at max load is 1.0075 !! I think I would have some serious stability issues at this voltage !
I've already overclocked to 3.6GHz and have had to manually adjust the Vcore up to 1.26875 in BIOS to get it to run Prime95 reliably. Everest shows Vcore of 1.248v under load, so, if I've got my Vid right as above, I'm already overvolting my CPU by 0.128v !
This can't be right. I think I've gone wrong in my assumptions but I don't know where. I hope someone has been down this track before and can shed some light on the subject.
P.S. Wish I could go back and buy a E8400 with Vid rating of 0.85v - would solve my problems.
The E8400 box showed the following:
Batch: Q745A740
sSpec: SLAPL
Version: E27439-001
Pack Date: 01/21/2008
1.225V Max
The '1.225V max' - Is this the Vid rating for my particular chip? If so, then is CoreTemp ver 0.97.1 displaying the wrong Vid of '1.1125v'. My BIOS default auto settings give a Vcore of 1.225v (coincidence or reading the Vid from the BIOS at boot and adjusting to suit?).
The Intel datasheets have some complicated way of trying to give the max Vcc. First off they say Vcc absolute max is 1.45v but this, quote 'lies outside the functional limits of the processor'. So what is the functional limits... I read on. Vid range set at manufacture time can be between 0.85 and 1.3625v. Vcc min and max are differences from Vid (depending on current draw) as shown in a graph.
Then, if I read the graph right, at 0A Icc, Vcc max = Vid. At max Icc (75A - wow!), Vcc max = Vid - 0.105.
So, if my Vid is 1.225v (as maybe shown on the box), then my Vcc max at max load is 1.12v.
And if I believe CoreTemp's Vid of 1.1125v, then my Vcc max at max load is 1.0075 !! I think I would have some serious stability issues at this voltage !
I've already overclocked to 3.6GHz and have had to manually adjust the Vcore up to 1.26875 in BIOS to get it to run Prime95 reliably. Everest shows Vcore of 1.248v under load, so, if I've got my Vid right as above, I'm already overvolting my CPU by 0.128v !
This can't be right. I think I've gone wrong in my assumptions but I don't know where. I hope someone has been down this track before and can shed some light on the subject.
P.S. Wish I could go back and buy a E8400 with Vid rating of 0.85v - would solve my problems.
1.5v is NOT safe for the average OC on the 45nm. There are degredation reports @ 1.45v+. And I dont mean from 20 years to 10, I mean from 20 years to 30 days. Personally, I wouldnt take a Wolfdale anywhere over 1.4V if I was planning on keeping it for a lengthy period of time. However, if you cycle your CPU out every 6-12 months, go for it!
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