CPU Bclk and voltages

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perdomot

Golden Member
Dec 7, 2004
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I'm working on finding out the limits on my new rig and decided to see if a 200 bclk on my Gigabyte H55 mobo was reasonable. I went into the bios and lowered my multi to 9, raised the blck to 200 and left all voltages to auto. When I got into windows, I checked cpu-z to find my vcore at 1.39! Considering that most reports on OCs with my i5 760 report between 1.25 and 1.3 vcore, this number seems way off. Can anyone explain why the auto setting set it so high? I went in manually to set the vcore to 1.3 and am Priming now without any problems so 200 appears OK and I have to figure out how high I can take the multi before voltages have to go up.
 
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iCyborg

Golden Member
Aug 8, 2008
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It's fairly well-known that auto voltages are being rather conservative on pretty much all BIOS-es. Most CPUs will work with much lower voltage, but the higher the value, the bigger the coverage of CPUs. I guess MB makers are going for the coverage.
 
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perdomot

Golden Member
Dec 7, 2004
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iCyborg said:
It's fairly well-known that auto voltages are being rather conservative on pretty much all BIOS-es. Most CPUs will work with much lower voltage, but the higher the value, the bigger the coverage of CPUs. I guess MB makers are going for the coverage.
Click to expand...

Thanks, didn't know that. Just did a little experiment comparing 200bclk X 16 versus a blck of 160 and a multi of 20. The lower blck didn't get as hot (69 vs 74) even though the frequency and performance(video encoding 290 FPS) were the same. Why would that be?
 
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Rifter

Lifer
Oct 9, 1999
11,522
751
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perdomot said:
Thanks, didn't know that. Just did a little experiment comparing 200bclk X 16 versus a blck of 160 and a multi of 20. The lower blck didn't get as hot (69 vs 74) even though the frequency and performance(video encoding 290 FPS) were the same. Why would that be?
Click to expand...

Always manually set your voltages when overclocking. The bios will set them high and thus generate more heat and use more power and limit your overclock.
 
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brencat

Platinum Member
Feb 26, 2007
2,170
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perdomot said:
I'm working on finding out the limits on my new rig and decided to see if a 200 bclk on my Gigabyte H55 mobo was reasonable. I went into the bios and lowered my multi to 9, raised the blck to 200 and left all voltages to auto. When I got into windows, I checked cpu-z to find my vcore at 1.39! Considering that most reports on OCs with my i5 760 report between 1.25 and 1.3 vcore, this number seems way off. Can anyone explain why the auto setting set it so high? I went in manually to set the vcore to 1.3 and am Priming now without any problems so 200 appears OK and I have to figure out how high I can take the multi before voltages have to go up.
Click to expand...

You again?? LOL. You keep messing with your system. Did you bother to read the 3-step Lynnfield overclocking guide from Techreaction that I linked you 2 wks ago?
 
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Kenmitch

Diamond Member
Oct 10, 1999
8,505
2,250
136
If you run your chip at stock speeds with C1E, SpeedStep, Turbo and Enhance halt state etc enabled what does your chip want? Voltages on Auto or Normal setting if available. You can just use prime or intel burn test to load 1 core to see the voltage.

I was playing around with my i5 750 last week to see what stock voltage gets me and this was what mine wanted and would do.

Stock speeds and voltages
  • 1.2ghz .870v Idle temp (25*C) GPU 29*C
  • 2.8ghz 1.200v 4 Core load (41*C) GPU 30*C
  • 3.2ghz 1.258v Single core load (38*C)
Overclocked 3.8ghz (CPU VTT 1.100v)
  • 1.63ghz .976v Idle temp (28*C) GPU 30*C
  • 3.80ghz 1.258v 4 Core load (52*C) GPU 31*C

The temps are from water cooling tho....The GPU temp was just to see how it effected water temp. At least in theory anyways.

I'd say just pick a comfortable max temp and play around till you find the sweet spot for your chip :)
 
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perdomot

Golden Member
Dec 7, 2004
1,390
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76
Spikesoldier said:
1.4v is still in spec for lynnfield.

on the spec sheet vtt can go as high as 1.4v also.
Click to expand...

Yeah, its the heat that worries me because my Xig 1283 can only handle so much. Probably gonna have to upgrade to something a bit stronger because I got my system at 3.5Ghz now and video encoding is taking it to 77C.
 
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perdomot

Golden Member
Dec 7, 2004
1,390
0
76
Kenmitch said:
If you run your chip at stock speeds with C1E, SpeedStep, Turbo and Enhance halt state etc enabled what does your chip want? Voltages on Auto or Normal setting if available. You can just use prime or intel burn test to load 1 core to see the voltage.

I was playing around with my i5 750 last week to see what stock voltage gets me and this was what mine wanted and would do.

Stock speeds and voltages
  • 1.2ghz .870v Idle temp (25*C) GPU 29*C
  • 2.8ghz 1.200v 4 Core load (41*C) GPU 30*C
  • 3.2ghz 1.258v Single core load (38*C)
Overclocked 3.8ghz (CPU VTT 1.100v)
  • 1.63ghz .976v Idle temp (28*C) GPU 30*C
  • 3.80ghz 1.258v 4 Core load (52*C) GPU 31*C

The temps are from water cooling tho....The GPU temp was just to see how it effected water temp. At least in theory anyways.

I'd say just pick a comfortable max temp and play around till you find the sweet spot for your chip :)
Click to expand...

Until I get better cooling, I'll have to stick with 3.5Ghz. I also noted that there is another setting in the Gigabyte Bios which affects the multiplier(C3/C6 states) and I decided to leave that on because it lowers my idle temps from 45 to 32C. I'll probably enable C1E and EIST once I find out what my rigs limits are.
 
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Kenmitch

Diamond Member
Oct 10, 1999
8,505
2,250
136
perdomot said:
Until I get better cooling, I'll have to stick with 3.5Ghz. I also noted that there is another setting in the Gigabyte Bios which affects the multiplier(C3/C6 states) and I decided to leave that on because it lowers my idle temps from 45 to 32C. I'll probably enable C1E and EIST once I find out what my rigs limits are.
Click to expand...

Sucks being thermally limited on overclocking. Main reason I went to water cooling was I hated my overclock being dictated by my temps! I'd rather the chip tells me when it's had enough.
 
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perdomot

Golden Member
Dec 7, 2004
1,390
0
76
Kenmitch said:
Sucks being thermally limited on overclocking. Main reason I went to water cooling was I hated my overclock being dictated by my temps! I'd rather the chip tells me when it's had enough.
Click to expand...

From what I've seen, I thought air cooling had really closed the gap in cooling with water. Most folks seem to be focused more on the water coolings acoustical advantage.
 
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