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Intel Core 2 on 45nm: Performance, Overclocking, Power Usage

CPU by piotke @ 2007-10-29

Intel is launching their successor the popular Conroe CPU, build on 45nm manufacturing process, it boasts reduced power consumption and has 50% more L2 cache. The first product out the door is a quad core beast dubbed QX9650. We take this new creation through its paces, comparing performance, power consumption and venturing into overclocking land, where sub zero cooling is the norm.

Introduction

Introduction

A little over a year ago we saw Intel take back the performance crown when they launched their new CPU based off the Pentium M series, dubbed “Core 2 Duo” this CPU held 2 physical cores inside one heatspreader, and it’s performance was stellar even at lower clock speeds. Build on 65nm process the Core 2 Duo could be manufacturered at reduced cost and proved to have quite a bit of headroom in the speed department. The top of the line model was the Core 2 X6800 clocked at 2.93Ghz with 4Mb L2 cache and 266Mhz FSB.

Since then more affordable CPUs have been added to the Core 2 line-up, with lower end models receiving less L2 cache to reduce cost, newer revisions released this year got a FSB bump to 333, and we have one in for test here today too, the Core 2 E6850 is clocked at 3Ghz (9x333) and has 4Mb L2 cache; this CPU surpasses the performance of the original X6800 but costs only ~$280 at time of writing. AMD has yet to reveal a CPU which can match the Core 2 in price/performance, and while Intel it still in the lead, they are not sitting by idly.

Back in October last year Intel released a press statement regarding the switch to 45nm manufacturing process, the 65nm CPU had a code name “Conroe”, the 45nm CPUs got a new one: Penryn. We are now at the end of October 2007 and Intel is going public with 45nm processors, you’ll see a large collection of reviews and articles on the web this week, covering not only the Penryn, but also its larger brother, the “Yorkfield”. The latter is a Quad Core CPU, and where the Penryn has 1x6Mb L2 cache, the Quad Core has 2x6Mb L2.

Madshrimps (c)

The CPU Intel provided us was an Engineer Sample of the QX9650 CPU, running at 3Ghz with 333 FSB (a multiplier of 9x), with an estimated retail price of $999. Still on socket 775 this new CPU should work on most recent motherboards.

Before we get started, a truly meant thank you goes out to Forcom.be for providing us with most of the hardware used in this review.

What we have in store for you today:

Madshrimps (c)

New Intel Core 2 Quad QX9650

Intel Core 2 Duo E6850

Motherboard compatibility and support

Performance comparison single/multi core with different applications and games

Power Usage and Temperatures

Overclocking and Performance Scaling

Let’s take a look at our test setup ->

Comment from Sidney @ 2007/10/29

Reading other reviews, it would seem the engineering sample tested at [M] requires more vcore than others. 4Ghz quad would now be common speed; no bragging right unless you see 5Ghz.

Comment from jmke @ 2007/10/29

yes that seems to be the case, but no faulting engineering samples, they are supposed to run without fault at rated speeds with default vcore, which this QX9650 did

Comment from Kougar @ 2007/10/29

2.0v for 4.9GHz? Would have loved to see what that did to the power consumption figures for that CPU!

Regarding the discrepancy with your power chart, I think that has something to do with the physical properties of the chip design. I suspect that at very high frequencies there is a thermal threshold that once neared the leakage increases dramatically. After which it will quickly reach the point where the chip ceases to function or function stably since the increased leakage raises the heat, and the heat only further increases the transistor leakage in a self-fulfilling cycle. I don't have any real proof other than my own experiences with my Q6600...

I am curious, I notice from that CPUZ image the ES QX9650 uses 1.20v at 3GHz. My own Q6600 does the same... so how far can you drop the voltage and have the QX9650 remain stable at 3Ghz? I got a Q6600 down to 1.5v, but somewhere below that point my Q6600 will show errors. Gigabyte unfortunately lacks most of the FSB voltage tuning ASUS boards offer, as some members on the XS forums claim to have reached 1.10v for 2.5-2.8Ghz speeds for Kentsfields. Would be interesting to note what effect the smaller process size and change in transistor materials would have on this for Penryn.

Comment from jmke @ 2007/10/29

Quote:

Originally Posted by Kougar

2.0v for 4.9GHz? Would have loved to see what that did to the power consumption figures for that CPU!

You can

last chart on this page: http://www.madshrimps.be/?action=get...&articID=6 36
386W vs 210W stock

Comment from Kougar @ 2007/10/30

Ah, nice! I had completely missed that, staring me in the face.

I guess I need to take more power measurements since the data I have on my Q6600 includes my video card...

Why not extend that same chart a bit more to the right though, and undervolt that puppy?

Comment from CFKane @ 2007/10/30

I'm a little surprised that you're talking about a discrepancy in the chart while you're mentioning the changed cooling solution in the same sentence. The die temperature is one of the most important factors for the CPU power consumption and if you switch to a solution which removes the heat more efficiently, you should expect reduced power draw even with a higher clock and voltage.

That's also the reason why the maximum current in the electrical specifications for CPUs significantly exceeds what you would get from dividing the TDP by the core voltage. It's given for the maximum die temperature, which you will (hopefully) never reach in a real world situation.

Bear that in mind when testing or comparing CPU power consumption: The room/case temperature and cooling solution have a major influence and the die temperature at a certain load is an interesting figure to report along the power draw (sadly missing in most reviews).

Comment from jmke @ 2007/10/30

Thank you CFKane for you post and welcome to the forums

since the temperature was the only large difference between the two settings we were not doubting that it was indeed the lower temperature which was causing the lower temps; but I've not seen any article on the web discussing this aspect of the power consumption... hence were a bit hesitant to include that statement.

Comment from jmke @ 2007/12/07

we also got word back from Intel explaining the power usage at different temperatures:

Quote:

Matty @ Intel:

Yes, the power consumption is reduced when the temperature of the processor is lowered.

There are many things that happen in a CPU when the temperature is changed and to elaborate further on the processor specific causes we have to look at the origin of the power consumption. We can divide the total consumed power into two main parts, static power (Ps) and dynamic power (Pd).

The static power consumption is what we usually call the leakage. In an ideal transistor, it should completely shut off the channel between the source-drain, gate-source and gate-drain. Transistors are far from ideal, and the current leaks between these parts and the substrate of the processor, and this is heavily dependent on the temperature.
For example, going from room temperature to 85C (~60C difference) increases the leakage power by a factor of more than 50. Thus, reducing the temperature with the same amount will make a huge impact on Ps.

Dynamic power consumption is emitted during the short amount of time that the transistor switches. Lower temperature reduces the resistance in the processor which results in shorter delay/faster switching of the transistors. Shorter delays and less noisy signals also reduce Pd.

I hope this explanation give you some clarity to the relation between power consumption and temperature. This can even be seen with air cooling: The power consumption is lower just after a load is applied compared to after a while when the temperature has levelled out, even though the load is the same.

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