Power consumption for E2140 vs E6750 at the SAME frequency?

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sunefred
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Power consumption for E2140 vs E6750 at the SAME frequency?

Post by sunefred » Thu Aug 30, 2007 7:26 pm

This might seem like a very specific question, but I am simply looking for an answer to the following. Does the lower intel CPU models draw equally much power if overclocked to the same frequency as a high cost model? Maybee someone has seen some power consumtion numbers on overclocked CPU's?

I'm having a hard time seeing any significant benefits of the E6750 over the E2140 given that they have the same multiplier, and they overclock to about the same frequency (8x400=3.2Ghz). But if the power consumption of the E6750 is significantly lower then the E2140 at say 3.2 Ghz, that would be a huge benefit for a cool and quite computer.
Last edited by sunefred on Fri Aug 31, 2007 4:56 am, edited 1 time in total.

Mikey
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Post by Mikey » Thu Aug 30, 2007 8:35 pm

Whilst i don't have any figures to back this up, the E6750 @ 3.2Ghz should run cooler than the E2140, given that less of an overclock is required.

Also, bear in mind the E6750 has 4 times as much L2 cache as the E2140 - 1Mb vs 4Mb.

aaa
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Post by aaa » Fri Aug 31, 2007 2:36 am

I don't think power consumption has anything to do with how much it is overclocked. It is all dependent on the final speed/voltage combination. So if the 2140 can reach 3.2ghz at the same voltage as the 6750 then it would probably use less power because of the reduced L2 cache.

Which highlights the cache difference between the two, a big deal performancewise.

Jason W
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Post by Jason W » Fri Aug 31, 2007 7:13 am

I am running the E6750 at 3.2GHz ( 400 x 8 ) on a GA-P35-DS3R motherboard. I have the CPU voltage set in the BIOS to 1.250V. CPU-Z reports the idle voltage to be 2.00, and at full load with Orthos the voltage drops to 1.168 (gotta love Vdroop!).

I have my RAM voltage set at +0.2V in the BIOS. All my other voltages are set at "Normal" whatever that is.

This setup is stable running Orthos for 8+ hours. My CPU cores don't go over 60 degrees Celsius according to Core Temp version 0.95.4 (which reports the correct E6750 Tjunction of 100 degrees Celsius). I have a Ninja Rev. B on the CPU, with a Nexus fan attached and spinning at 750 RPM.

Unfortunately I do not know how to measure the power draw in watts, either at idle or under load. Is there a software program out there that measures this?

Regards.

Jason

bendit
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Post by bendit » Fri Aug 31, 2007 8:05 am

when you undervolt a core2duo chip or allendale does speedstep still work the same? thanks

Deliriou5
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Post by Deliriou5 » Fri Aug 31, 2007 8:35 pm

Jason W wrote: I have the CPU voltage set in the BIOS to 1.250V. CPU-Z reports the idle voltage to be 2.00, and at full load with Orthos the voltage drops to 1.168 (gotta love Vdroop!).
Jason, I'm kind of confused about what you're saying. Are you saying that even though you set the voltage in the BIOS to be 1.250, it is instead idling at 2.00 volts? Are you further saying that at full load that 2.00 volts now "drops" to 1.168 volts? This seems counter intuitive, or I'm missing something here. What else is going on?

Thanks,
-Deliriou5

fresh
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Post by fresh » Sat Sep 01, 2007 12:11 am

Bios Vcore value is the precise one, or at least in most cases (some motherboards have that all messed up). I have the same situation. My e4500 is run at 1,2V, whereas cpu-z reports really confusing voltages. It's probably because cpu-z hasn't had data written for newer procesor yet.

Power consumption of procesor is equivalent to frequency and voltage, but it is also very important to know that the older revisions of CPUs, such as B2, have higher power consumption in IDLE as well as in LOAD at the same configuration. Newest, the M0 revision, is said to be the one with the lowest power consumption.

So, in my opinion both E2400 and E6750 should have similar power consumption at the same clocks and same voltages, given they are same of the revision. One could take in importance that lower L2 cache consumes less power, but that is overthroven since it also make it a bit slower, so computer needs more time to calculate 'stuff and is therefor more time present in the state of LOAD and consumes a bit more power.... and so on...

smilingcrow
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Post by smilingcrow » Sat Sep 01, 2007 10:31 am

sunefred wrote:I'm having a hard time seeing any significant benefits of the E6750 over the E2140 given that they have the same multiplier, and they overclock to about the same frequency (8x400=3.2Ghz).
From what I’ve seen the E2140 (L2) doesn’t usually overclock as well as the 333FSB (G0) C2D chips at stock voltage, so 3.2GHz seems unrealistic. I’m not sure if the G0 revision E2140 closes the gap!
Keep in mind that for certain applications (games are one) the 1MB cache of the E2140 seriously affects performance.
Personally I think that the E4x00 series chips are a good compromise as they have 2MB caches and higher multipliers. The E4500 has a multi of 11 so hits 3.2GHz with a FSB of only 291 and the yet to be released E4600 will hit 3.2GHz at only 266 FSB. They are both M0 revisions which seem comparable to G0; not sure how high they will go at stock VCore though.
Using a lower FSB speed helps reduce power consumption and heat so is also worth considering.
Bendit wrote:when you undervolt a core2duo chip or allendale does speedstep still work the same? thanks
If you under-volt using software (e.g. RMClock) then Speedstep still works normally. If you under-volt in the BIOS typically the VCore is fixed although Speedstep will still modulate the Clock speed.

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