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Sandy Bridge Undervolts

D

djkest

Limp Gawd
Joined
Nov 30, 2007
Messages
349
Hey guys,
Looks like a lot of people are overvolting and overclocking. Anyone tested the limits of undervolting?

I got my i5-2400 stable at 1.085V Vcore, which dropped my power consumption quite a bit! I will do more testing as I have time.

Would love to see what other people are getting for results. MSI has very good voltage intervals on the H67 board I purchased.
 
I undervolt mine too,
loving it :p

BIOS setting 1.07V LLC disabled,
Motherboard : Biostar TH67+
llcdisable1068vcore107v.png


HTML: 
http://img853.imageshack.us/img853/8765/llcdisable1068vcore107v.png

im on stock cooler btw
 
Trying to undervolt mine now,

what Bios settings are you using djkest,

I'm using an MSI H67MA-E45 and so far using some power saving options gives me a horrible whine coming from one of the chokes.

I've got C-State and EIST on atm, apparently that's disabled my turbo boost, but I can't check because Real temp isn't reporting values correctly and I also seem to be topping out at 3093mhz during prime at 1.208v

any help on bringing these numbers down would be greatly appreciated.

Also, ahfu, how have you managed to get 3194mhz with 4 cores loaded?
 
turbo boost for i5-2400 h67.
1 bin = 100mhz

4 core = 1 bin---> 3.2gHz
3core = 2 bin
2 core =2 bin
1 core = 3 bin ---> 3.4ghz

If u lower voltage, the current within the phase will be very high. SO, it is better to turn on full phase ON to spread out the current, i believe.

C-state and EIST shouldnt disable the turbo boost.

try to disable Load line calibration first as it sometimes lowers the vcore instead.

I set mine to fixed voltage, if u are using a negative offset approach, it might lower too much for idle.
 
Currently undervolting + overclocking my new Core i5 2400.

Got it running now @ 1.05V and +4 Turbo. It completed 30 runs of IntelBurnTest and it is now pounding out Prime 95 Stress Tests @ 3.6GHZ w/ all four cores maxed out. 62C max temp so far on the stock cooler :D

Before undervolting I had the CPU voltage set to [Auto]. It was kicking up to 1.35V and it hit 93C when running Prime 95 :eek: I can't believe they have the stock VIDs on these chips when the stock cooler is easily overwhelmed. If this passes Prime for a few more hours, I am going to drop down to 1.025 and keep testing.
 
ahfu: I have no idea what negetive offsets and load line calibration is, if you could help out at all that would be appreciated,

basically, I'm trying to get this to throttle right down when idle and web using and then to max when needing heavy loads.

I'm using an MSI H67MA-E45, but so far, even with EUP2013 disabled and C-state enabled, I'm getting horrible electrical whine and differing reports from CPUZ and Realtemp.

Realtemp is saying my multi is constantly flapping around up and all over the place whereas CPUZ gives it either 16x 99.8mhz - 1696mhz then at 100% load under Prime, the electrical whine disappears and both Realtemp and CPUZ report 32x99.8 - 3192 mhz.

So I'm at a loss as to whether CPUZ is right, and Realtemp isn't reporting idle clocks properly, or Realtemp is right, and its not throttling down fully during idle.

of course, none of this is helped by MSI control center, which you can click any option and nothing changes, except voltages and multipliers, and even this resets after restarting the computer.

any ideas?


ocellaris: the i5 2400 can't do 3.6ghz even on one core, so how did you manage that?
 
lunatyc420 said:
ocellaris: the i5 2400 can't do 3.6ghz even on one core, so how did you manage that?
Click to expand...

You can overclock all non-K chips on a P67 motherboard by increasing the Turbo multipliers to +4 higher than stock. My my stock Turbo with 4 cores maxed would normally be 3.2GHz (32x100), and with the +4 its 3.6 (36x100).

When less cores are active it gets up to 3.8 GHz.
 
Just tried updating to Realtemp 3.67,

so far still no change with the multiplier readout, although it's recognizing the CPU ID now.

Is the Wattage read out on the front reliable at all, because even on stock 1.16v at 100% load through prime, i'm topping at under 60w and at idle, 7.1-7.5w

Which, coming from a 3.6ghz i7 920 is a lot of saving for not a lot less performance

ocellaris: well god damn, I knew i should of got a p67 board.

Is electrical whine enough for an RMA / changeout?
 
lunatyc420: Have you gone into the Control Panel - Power Options and reduced the Minimum processor state to a low number like 5%? That's what controls the multiplier at idle. If RealTemp is showing your multiplier going up and down at idle then it is going up and down.

You can also use ThrottleStop to monitor the average multiplier for each thread of your CPU.

http://www.techinferno.com/downloads/?did=1

At idle or when lightly loaded, CPU-Z bends the truth for consistent validation purposes so what it shows is not always an accurate look at what your CPU is doing internally.

There is a button in ThrottleStop that can be toggled from C1/C3/C6/C7 which can change the CPU whine but unfortunately this feature is locked on some of the newer Sandy Bridge motherboards.
 
unclewebb said:
lunatyc420: Have you gone into the Control Panel - Power Options and reduced the Minimum processor state to a low number like 5%? That's what controls the multiplier at idle. If RealTemp is showing your multiplier going up and down at idle then it is going up and down.

You can also use ThrottleStop to monitor the average multiplier for each thread of your CPU.

http://www.techinferno.com/downloads/?did=1

At idle or when lightly loaded, CPU-Z bends the truth for consistent validation purposes so what it shows is not always an accurate look at what your CPU is doing internally.

There is a button in ThrottleStop that can be toggled from C1/C3/C6/C7 which can change the CPU whine but unfortunately this feature is locked on some of the newer Sandy Bridge motherboards.
Click to expand...

I spent so long looking for that last night and only stumbled across older versions. Thanks for the link!
 
All I did was adjust the core voltage. I did not try anything else. I've been doing a lot of gaming and some prime95 @ 1.06 volts, I have my new cooler installed, and now it's "ice cold".

Idle: 18-20 C
Load: 36C

Lol!
 
What cooler are you using?

My i5 is stress testing @ 1.045v right now. It's been failing Prime 95 after a few hours when set lower than that.
 
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