tdp performance cost ratio: which processor?

[baijxz]

Which is currently the best cpu when one wants a reasonable performance/cost and least heat?

I've been browsing the TDP to Clock Speed Ratio (W/GHz)
but since there is no performance/price data in there it isn't really useful.

Btb. I'm weighing options for a decent performer for workstation duties; ie. autocad, photoshop/indesign/illustrator.

It might be an AMD for all I care I just want decent performance/low tdp and reasonably cheap.
I've looked at the core 2 duo s' models but they don't seem to compare favourably to the I5's

 

[rusi]

Core i5-750 specially when bought for $150 at MC.

If 95W is too much for you then get the Phenom II X4 905e

 

[blivit4]

TDP is about useless for what you want to know. It is a specification for how much heat the chip package can dissipate. What you really want to know is how much power the PC will use under load and at idle depending on which CPU is used. All else being equal, power usage will also depend on what mother board is used.

In general the new the CPU, the more power efficient it will be.

AMD based systems are considerably less power efficient than Intel ones. Photoshop benchmarks run faster on Intel based systems. AMD CPUs are good good for low priced systems, not low power or performance.

 

[drescherjm]

I think this is useless since. TDPs are not accurate and clock speed does not equal performance. If it did the 3.8GHz P4 would be a really great chip.

 

[drescherjm]

I think what is more important is performance / W. Back in the days of the P4/ P4D AMD was king since intel had a very power inefficient design. However now Intel beats AMD in this quite easily. One reason is IPC, it takes AMD 3.4 GHz to match the performance in Intel's 2.66 GHz i7. The other is transistor design.

 

[drescherjm]

then get the Phenom II X4 905e

I disagree. Any "energy efficient" chip in my opinion is not that great of a deal. For these both AMD and Intel take one of the higher end chips and undervolt and underclock it so that they can fit in a lower TDP category. The problem with this is since it is running slower it has to run at top speed more often instead of finishing early and going to idle mode where power consumption is under 20W. This scheme may save a little power but its not going to be that significant and if the user wants you can usually force an non factory underclocked /undervolted cpu to never hit the high p states through software.

 

[4x4not]

I'm not sure about a definitive answer to your question, but from experience the Athlon II x2 chips are very cheap (~$50) and don't pull a ton of power, especially when using Cool 'n' Quiet. My HTPC is running an Athlon II x2 245 and the entire system pulls less than 60w at idle (pretty much anything but HD playback), and this is using a fairly inefficient ITX power supply. This compared to the WHS machine in my sig which is pulling ~100w under normal operations, and the i7 machine which pulls ~160w at idle.

 

[drescherjm]

My HTPC is running an Athlon II x2 245 and the entire system pulls less than 60w at idle

A 3GHz core2 quad Q9650 only pulls around 60W idle with a single hard drive, 4 GB of ram and a nvidia 8400GS video card and a dvd writer.

and the i7 machine which pulls ~160w at idle.

You probably have a high end video card in the i7.

 

[baijxz]

wow a lot of replies, thank you for your time

I agree with the notion that TDP probably not is the most ideal solution for finding a power/performance ratio, but isn't that the only power usage specification given by the chipbuilders?
-How much power does a typical motherboard eat at idle and full tilt?
I surmise that chipset power consumption would have something to say, in that case I might be having some fun comparing the newest chipsets.

I'm not certain I disaprove of factory underclocked/undervolted cpus.
If they deliver the performance they solicit, then what is the problem?
Whether or not the cpu enters the highest performing state is of little concern as long as its power consumption at full load is still comparatively low.

 

[drescherjm]

Whether or not the cpu enters the highest performing state is of little concern as long as its power consumption at full load is still comparatively low.

My point with these is since these chips are limited to this lower state than they can handle they will stay longer in the lower state than they would if this limit would not exist. As a result of staying longer in this lower state the savings in total power used for a given task is diminished because if the job had finished earlier the CPU would have entered the idle state which is a much lower power state (typically 7 to 20W on current CPUs) than the full load state.

Also for any chip the user can download software and make it an e chip on their own if they believe running the chip slower will save them a lot of power. Heck if you want you can set your max frequency at the idle speed and voltage..

 

[blivit4]

You want efficient? Read this:

Maximum Efficiency: Build A 25W Performance PC Using Core i5

Intel does publish the idle power draw for their CPUs. However, even that number is very general, because actual power draw is very dependent on a specific chip's VID. Since load power draw depends on the software being run, and the environment, there is no standard Max Power.

If you look at this piece at Tom's you'll see that MB power draw depends on what's been added to the MB and BIOS settings. Every one is using the same chip sets (P55, H55 & H57).

 

[JamesL]

I'd say wolfdale. Something like an e8400 maybe

My cpu fan is running at 30%, and my overclocked e6750(conroe) temps are barely higher than room temp.