Downcoring - 940 Faster and Cooler

Frank_Rizzo · 1 Jun 2009 at 12:19

Just tried the downcore feature of the M3A78-T

Core Temp now 5' lower and I can squeeze an extra 0.5 out of the multiplier.

PC is running faster, cooler and cheaper so makes me wonder why bother with the 4 cores in the first place?

Seems crazy that to make your PC better value you have to switch off some of the features

Note - not a gaming rig so don't know if there would be an advantage in turning cores off for games. Certainly for database / general use this is now a better performing rig with 2 cores turned off.

Ross1234 · 1 Jun 2009 at 12:27

Why did you buy that processor if your not going to utilise it and turn off its features?

Glaucus · 1 Jun 2009 at 12:28

wtf are you crazy.

reflux · 1 Jun 2009 at 12:30

Frank_Rizzo said:
PC is running faster, cooler and cheaper so makes me wonder why bother with the 4 cores in the first place?

Seems crazy that to make your PC better value you have to switch off some of the features .

...or you could just spend less on the CPU in the first place, and get one designed for the 'value' segment?

I'm sure any performance you've seen as a result of decreasing the power is merely a placebo.

UKDTweak · 1 Jun 2009 at 12:30

How does switching off half the cores make it better value, you now have an overprice dual core LOL...
Half the cores running a little faster in single thread apps may be faster with a higher clock, but in multi threaded apps you Fail!!!

Frank_Rizzo · 1 Jun 2009 at 12:48

If AMD produced a 2 core Phenom II I can assure you I would have bought it

My own benchmarks show faster speed and at cooler temps. Apps not designed for 4 core so pointless in using them. This is the point I am making: by turning off some features I have a faster, cooler rig. It's ironic.

JonJ678 · 1 Jun 2009 at 12:59

Good feature. Looks like a step beyond having an underclocked and an overclocked profile (the slow one makes rather less noise).
I'm more surprised that it only made 5 degrees difference, if it was properly turning off the cores I'd hope to drop the power consumed by the processor by a third at least, which would be more than 5 degrees I think

Happy · 1 Jun 2009 at 14:05

reflux said:
...or you could just spend less on the CPU in the first place, and get one designed for the 'value' segment?

I'm sure any performance you've seen as a result of decreasing the power is merely a placebo.

As said by reflux, there's no way that by disabling 2 cores the remaining two run any faster than before (unless you have then overclocked them). Also I love the bit where by you mention that it's cheaper to run, if you really cared then you would have got a dual core for far less money in the first place.

Frank_Rizzo · 1 Jun 2009 at 15:38

Happy said:
As said by reflux, there's no way that by disabling 2 cores the remaining two run any faster than before (unless you have then overclocked them). Also I love the bit where by you mention that it's cheaper to run, if you really cared then you would have got a dual core for far less money in the first place.

I think I said by disabling the two cores I could get a better O/C.I did not say that disabling the two cores makes the chip run instantly faster as is ...

Surely if I'm running on less power now then it is cheaper to run than previously.

Point of this thread is to show the irony of this.

Less is more.

reflux · 1 Jun 2009 at 15:42

Oh I see what you mean - what's your core speed now as opposed to before?

Bear in mind that any power draw reduction will only save you a few pennies over the year.

Happy · 1 Jun 2009 at 15:45

Frank_Rizzo said:
I think I said by disabling the two cores I could get a better O/C.I did not say that disabling the two cores makes the chip run instantly faster as is ...

Surely if I'm running on less power now then it is cheaper to run than previously.

Point of this thread is to show the irony of this.

Less is more.

I apologize I didn't see you mention you have overclocked it

However it still begs the question regardless if you save a few quid a year on leccy, why buy a more expensive quad to begin with if you're going to turn 2 core off?

Frank_Rizzo · 1 Jun 2009 at 15:52

Getting 3.6 now, previously 3.5. I'm not a serious clocker. Just content to o/c the multiplier only and leave the voltages, nb, mem speeds on defaults.

But the temp drop of 5' is more significant.

I recently put it in a CM 335 with 2 x 120mm fans replacing an old Lanboy with 3 x 80mm and the temps did not change much.

This is why I experimented with the downcores. Found that with my apps I'm getting better performance / value out of it than previously.

If anyone else has one of these chips / boards with DC facility and are worried about temps / noise then there is no need to stop O/Cing - just turn off some cores (unless you are running apps or games which use all cores).

Mattus · 2 Jun 2009 at 00:54

Frank_Rizzo said:
Getting 3.6 now, previously 3.5. I'm not a serious clocker. Just content to o/c the multiplier only and leave the voltages, nb, mem speeds on defaults.

But the temp drop of 5' is more significant.

If you were going to disable half the CPU, why didn't you just get an E8xxx and clock it to 4Ghz+? Would have been cheaper, cooler, less power hungry and just as fast. Buying a high-end CPU and switching half of it off strikes me as pretty silly.

Frank_Rizzo · 2 Jun 2009 at 08:53

Another one who just doesn't get the theme of this thread. I'm getting to think it is me being welsh but having lived in England for the past 15 years. Like my typing accent is not clear or something

Buying a high-end CPU and switching half of it off strikes me as pretty silly

The point is that I managed to get even better performance out of my existing rig.

I was very pleased with the performance when I first got it and O/Cd out of the box. Now, after a simple modification I am extremely pleased with the performance / value of the 940.

Happy · 2 Jun 2009 at 10:36

Ok, fair enough but did you try overclocking it when all four core were enabled? If so how far did you get.

Frank_Rizzo · 2 Jun 2009 at 10:58

Yep. Could not get past 17.5x previously. Turning 2 of the cores off can now get 18.5 without any other changes required.

The temp change was the key thing for me though.

4 cores @ 17.5x : 55-57' on full load
2 cores @ 18.5x : 50-51' on full load

Glaucus · 2 Jun 2009 at 11:09

LOl so you mess your cpu but yet because of a placebo you hink it runs beter. a 0.1 overclock wow.

still not getting this thread or the irony.

JonJ678 · 2 Jun 2009 at 11:24

I still think the option is a good one to have available. Have one heavily overclocked profile, and a second undervolted, underclocked, and now half the processor disabled profile. Even a single core of the i7 running at 2ghz is more than capable of playing a film, and would throw out very little heat

Mattus · 2 Jun 2009 at 11:37

Frank_Rizzo said:
The point is that I managed to get even better performance out of my existing rig.

The point is that if your rig is faster with half its CPU turned off, you obviously bought the wrong CPU in the first place. Why spend £230 on a chip that can run eight simultaneous threads if you don't really multitask?

Frank_Rizzo · 2 Jun 2009 at 12:25

If I could have found an AMD 2 core which:

hit 3.7Ghz out of the box (just upping the CPU multiplier)
using standard case fans on slow speed
cost £200 on release
works with RAM running at 1066

I probably would have bought it!

Unfortunately no such device existed. I went for the 940 rig. Later I found could get better performance out of it* with lower temps purely by turning off half the engine.

*note: my apps. Some will not see the same performance / value increase by turning off cores.