Intel's Core 2 Extreme QX6700: The Multi-core Era Begins
by Anand Lal Shimpi on November 2, 2006 2:14 AM EST- Posted in
- CPUs
Performance per Watt Comparison
3dsmax 7
3dsmax, like many 3D renderers, absolutely loves more cores and here we see Kentsfield maintain a tremendous performance advantage over Conroe. The scores reported are the SPECapc 3dsmax rendering composite in points, higher numbers being better, but the most interesting values are the performance per watt numbers.
Note: we are looking at system power draw rather than trying to isolate just the CPU. In that sense, we are comparing potential of running quad core configurations - i.e. in render farms and the like - instead of more dual core systems. Were we to get just the CPU power usage numbers, we would expect the usage of two identical cores in a single package to basically double power draw.
| CPU | Performance |
Average Power Consumption | Performance per Watt |
| Intel Core 2 Extreme X6800 (2.93GHz) | 4.11 pts | 192.5W | 0.0214 pts/W |
| Intel Core 2 Extreme QX6700 (2.66GHz) | 6.59 pts | 230.5W | 0.0286 pts/W |
| Intel Core 2 Duo E6700 (2.66GHz) | 3.77 pts | 189.2W | 0.0199 pts/W |
| Intel Core 2 Quad Q6600 (2.40GHz) | 5.96 pts | 225.9W | 0.0264 pts/W |
| Intel Core 2 Duo E6600 (2.40GHz) | 3.39 pts | 184.4W | 0.0184 pts/W |
| Intel Core 2 Duo E6300 (1.86GHz) | 2.68 pts | 176.1W | 0.0152 pts/W |
| Intel Core 2 Single Core (2.40GHz) | 1.85 pts | 174.1W | 0.0106 pts/W |
With higher performance and higher power consumption, the two manage to balance out and result in better performance per watt out of the two Kentsfield based parts than any of the dual core CPUs. While Kentsfield does require more power than Conroe, you get an even larger increase in performance thus resulting in a more efficient overall CPU.
Let's see if this is the start of a trend...
Cinebench 9.5
The Cinebench 9.5 test is also a multithreaded 3D rendering benchmark that will take advantage of as many cores as are present in the system. For each core, Cinebench spawns an additional renderer to help speed up the rendering of a static scene. Performance goes up by over 60% when moving from two to four cores, but once again it's the performance per watt that is particularly interesting:
| CPU | Performance |
Average Power Consumption | Performance per Watt |
| Intel Core 2 Extreme X6800 (2.93GHz) | 892 pts | 189W | 4.719 pts/W |
| Intel Core 2 Extreme QX6700 (2.66GHz) | 1337 pts | 225.1W | 5.939 pts/W |
| Intel Core 2 Duo E6700 (2.66GHz) | 816 pts | 186.1W | 4.384 pts/W |
| Intel Core 2 Quad Q6600 (2.40GHz) | 1216 pts | 219.8W | 5.532 pts/W |
| Intel Core 2 Duo E6600 (2.40GHz) | 751 pts | 181.8W | 3.973 pts/W |
| Intel Core 2 Duo E6300 (1.86GHz) | 582 pts | 175.4W | 3.127 pts/W |
| Intel Core 2 Single Core (2.40GHz) | 402 pts | 172.2W | 2.334 pts/W |
None of the dual core CPUs can come close to touching the power efficiency of the quad core Kentsfield based offerings.
DivX 6.1
Media encoding applications were the first to get a performance boost from dual core CPUs, but the impact is not nearly as great when we move to quad core processors. There's a gain of around 38%, which is by no means bad, just simply not as great as what we saw in the previous 3D rendering tests. The end result is that performance per watt is a lot closer between the most efficient dual core CPUs and the new quad core offerings:
| CPU | Performance |
Average Power Consumption | Performance per Watt |
| Intel Core 2 Extreme X6800 (2.93GHz) | 19.4 fps | 189.2W | 0.1027 fps/W |
| Intel Core 2 Extreme QX6700 (2.66GHz) | 24.8 fps | 223.7W | 0.1108 fps/W |
| Intel Core 2 Duo E6700 (2.66GHz) | 18.0 fps | 185.7W | 0.0968 fps/W |
| Intel Core 2 Quad Q6600 (2.40GHz) | 24.0 fps | 220.0W | 0.1089 fps/W |
| Intel Core 2 Duo E6600 (2.40GHz) | 16.3 fps | 183.0W | 0.0864 fps/W |
| Intel Core 2 Duo E6300 (1.86GHz) | 13.8 fps | 176.9W | 0.0745 fps/W |
| Intel Core 2 Single Core (2.40GHz) | 11.2 fps | 170.7W | 0.0658 fps/W |
If we look at performance per watt per transistor, Kentsfield is really not doing well here at all, despite an increase in performance and a continued advantage in performance per watt.
Windows Media Encoder 9
We see a much stronger showing from Kentsfield in the WME9 test, indicating that the DivX test was not representative of all media encoding on quad core.
| CPU | Performance |
Average Power Consumption | Performance per Watt |
| Intel Core 2 Extreme X6800 (2.93GHz) | 61.5 fps | 189.1W | 0.3252 fps/W |
| Intel Core 2 Extreme QX6700 (2.66GHz) | 86.4 fps | 223.2W | 0.3870 fps/W |
| Intel Core 2 Duo E6700 (2.66GHz) | 55.8 fps | 184.5W | 0.3025 fps/W |
| Intel Core 2 Quad Q6600 (2.40GHz) | 78.9 fps | 218.6W | 0.3608 fps/W |
| Intel Core 2 Duo E6600 (2.40GHz) | 50.4 fps | 181.8W | 0.2665 fps/W |
| Intel Core 2 Duo E6300 (1.86GHz) | 39.4 fps | 176.9W | 0.2137 fps/W |
| Intel Core 2 Single Core (2.40GHz) | 31.3 fps | 171.7W | 0.1822 fps/W |
Quicktime (H.264)
Interestingly enough, our Quicktime H.264 test didn't show any performance improvement going from two to four cores, indicating that the encoding process is optimized for two threads. Quicktime thus becomes the posterchild for what's necessary for the multicore revolution to truly bring about greater power efficiency: better threading within applications.
| CPU | Performance |
Average Power Consumption | Performance per Watt |
| Intel Core 2 Extreme X6800 (2.93GHz) | 30.0 fps | 191.2W | 0.1569 fps/W |
| Intel Core 2 Extreme QX6700 (2.66GHz) | 27.5 fps | 210.0W | 0.1309 fps/W |
| Intel Core 2 Duo E6700 (2.66GHz) | 27.5 fps | 188.1W | 0.1461 fps/W |
| Intel Core 2 Quad Q6600 (2.40GHz) | 25.2 fps | 207.0W | 0.1216 fps/W |
| Intel Core 2 Duo E6600 (2.40GHz) | 26.5 fps | 185.1W | 0.1430 fps/W |
| Intel Core 2 Duo E6300 (1.86GHz) | 19.8 fps | 177.7W | 0.1113 fps/W |
| Intel Core 2 Single Core (2.40GHz) | 16.2 fps | 170.6W | 0.0951 fps/W |
Here the dual core offerings are clearly superior when it comes to performance per watt simply because the Kentsfield CPUs aren't able to outperform them, all while using more power. The efficiency wouldn't be a problem if Kentsfield was able to power down unused cores independently of one another.
iTunes MP3
Our final test is yet another benchmark that only spawns two encoding threads, and we get another example of how power efficiency falls off if the software is not threaded enough to match the CPU's resources.
| CPU | Performance |
Average Power Consumption | Performance per Watt |
| Intel Core 2 Extreme X6800 (2.93GHz) | 11.7 MB/s | 193.4W | 0.0605 MBps/W |
| Intel Core 2 Extreme QX6700 (2.66GHz) | 10.9 MB/s | 213.1W | 0.0509 MBps/W |
| Intel Core 2 Duo E6700 (2.66GHz) | 10.5 MB/s | 188.3W | 0.0557 MBps/W |
| Intel Core 2 Quad Q6600 (2.40GHz) | 9.8 MB/s | 206.8W | 0.0474 MBps/W |
| Intel Core 2 Duo E6600 (2.40GHz) | 9.8 MB/s | 185.4W | 0.0529 MBps/W |
| Intel Core 2 Duo E6300 (1.86GHz) | 7.6 MB/s | 177.0W | 0.0429 MBps/W |
| Intel Core 2 Single Core (2.40GHz) | 6.1 MB/s | 168.4W | 0.0361 MBps/W |
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Staples - Thursday, November 2, 2006 - link
I will eventually be buying an E6600 but I was hoping we'd see a price drop when these quad cores came out. Now they have and we see that the cheapest one is over $800, the price of the E6600 will probably not drop for a while because these processors are not in the same market.rqle - Thursday, November 2, 2006 - link
Price doesnt really interest me as much, the fact that i have a very hard time getting a lot of low end Athlon64 around 2.8ghz, mines seem to max out at around 2.7ghz. Seem like most athlon for some reason like 2.3-2.4 and sometime lower while a whole group at my lan party have no problem push a E6300 past 3.1ghz.Brunnis - Thursday, November 2, 2006 - link
The article seems to state that Kentsfield is more efficient that Conroe. This conclusion comes from power measurements of complete systems. This is a little misleading, since a large chunk of that power is consumed by the rest of the system. Since the CPU only makes up a part of the power consumption, but accounts for a very large performance increase, the efficiency is bound to increase when looking at system power consumption.The Kentsfield CPU itself shouldn't be any more efficient than Conroe. That said, there isn't anything wrong in looking at system power consumption and drawing the conclusion that the computer is more efficient with the quad core. I just don't think that the article was very clear on this, though.
smilingcrow - Thursday, November 2, 2006 - link
The power efficiency figures would look different if a lower power PC had been used as a test bed; the use of dual X1900XT cards distorts the figures to a degree. These CPUs are currently only particularly useful for areas where Crossfire setups are not generally relevant.I used the Anandtech data along with my own C2D data from testing low power systems and came up with the following. The extrapolated figures show the efficiency of each CPU as a percentage of that of the QX6700, which is the most efficient in these two tests:
CPU/Anand PC/My PC
3dsmax7
QX6700 – 100/100
Q6600 – 92.3/92.9
X6800 – 74.7/80.7
E6700 – 69.7/75.7
DivX 6.1
QX6700 – 100/100
Q6600 – 98.4/99.01
X6800 – 92.5/99
E6700 – 87.4/94.4
The PC I used for a comparison uses ~60W less at load than Anandtech’s setup which results in:
130W v 189W for the E6700
172W v 230.5W for the QX6700.
System - Asus P5W DH Deluxe, Nvidia 6200TC, 2 x 1GB DDR2-667, Samsung P120 250GB SATA.
The one thing that was missing for me was the power consumption at idle, as I’d imagine that the dual Dice Kentsfield would take a big hit here. Xbitlabs have figures showing idle power consumption, but they are measured with C1E & EIST disabled which makes them a bit pointless in my eyes. Kentsfield gets a spanking in this comparison although it matches an FX-62.
EnzoM3 - Thursday, November 2, 2006 - link
I can only make assumptions, without any test beds here. Since Quad core is simply two dies of Conroe as this article pointed out, the power consumption of the Quad core should double that of Core Duo. If you use that assumption to compute performance per watt, regardless of what the actual numbers are (as long as Quad uses twice the power of Duo), then Quad actually has lower performance per watt than Duo across the board.Sunrise089 - Thursday, November 2, 2006 - link
If you could isolate the CPU only, you're certainly correct, and PPW will decrease with each additional core due to diminishing returns from scaling. Fortunatly CPUs are part of an entire PC, so when the choice can be painted as quad-core versus two dual-core machines, then the numbers look much better.ATWindsor - Thursday, November 2, 2006 - link
Yeah i agree, the more the rest of the system uses, the more "flawed" the numbers will be, lets say, for arguments sake, that a CPU uses 50 watts, and a twice as fast one uses 200 watts. Tut the rest of the system uses 300 watts, then the total system will use 350 watts in the fist case, and the twice as fast one will use 500 watts, so if you take the whole system numbers, the more power-hungry core will seem like it gives more permformanve per watt, but if you only look at the CPUs them self, the picture is diffrent, the less powerhungry CPU has twice the performance per watt.JarredWalton - Thursday, November 2, 2006 - link
You are right that we could be more clear. You can think in terms of efficiency that we're looking at two dual core systems vs. one quad core if you'd like. If we could isolate just the CPU power draw, we could get real CPU efficiency, but doing so is very difficult.PrinceGaz - Thursday, November 2, 2006 - link
Some sites have indeed isolated the CPU power draw by modifying mobos so that current draw as well as voltage on certain pins can be measured. It is, as you say, very difficult however and each platform you wish to test needs its own modded mobo.One simpler way to at least get a rough idea of actual power comsumption (which could be easily calibrated to provide more accurate figures), and a quite accurate measure of relative power consumption would be to measure the heat given off rather than the electricity going in.
The most obvious way to do that would seem to be with a modified water-cooling setup where instead of the heat being dissipated by an external radiator into air, it is instead transferred into a *large* insulated tank of water with an accurate digital thermometer monitoring the water temperature. This tank of water is not circulated through the water-cooling system, it is there merely for the heat to be dumped into. You then measure the rate at which the temperature rises which provides a good guide to power consumption. You might start at 20C and could probably run the tests up until the water reaches about 40C without any problems, probably 45C would still result in the CPU being kept within safe temperatures.
With a 10-litre tank, you would have 10Kg of water, and each Kg requires about 4.2KJ of energy to heat up by 1C, so it would take about 42KJ to heat up that tank of water by 1C. 42KJ is equivalent to 42KW for 1 second, or more realistically, 42 watts for 1000 seconds (about sixteen and a half minutes). You can probably see where I'm going here: a processor using about forty watts of power would heat up the tank of water by about 4C per hour. Eighty watts would be 8C per hour, and so on. Although not all the energy used by the processor will be dumped in the water due to heat being lost elsewhere, the vast majority of it will be and it will be consistent between different processor models.
If you want an exact figure for power consumption, or rather heat dissipation, then the system could be calibrated by connecting it to a CPU shaped heater element fed with a measured amount of power. Take measurements of the rate of temperature rise at twenty watt intervals up to say two hundred watts (I suspect the line will be fairly linear above about 40W) and you can now say with a good degree of accuracy how much power a given CPU is actually using.
As I say, that's one way you could do it and one which in theory should work very well.
Furen - Thursday, November 2, 2006 - link
Wow, that's a insanely round-about way of measuring power draw. You can also measure voltage and current draw at the CPU voltage VRMs. Regardless, CPU power draw truly doesn't matter with this product since it is two of the older products packed into a single package, no new silicon or anything of the sort. What this means is that theoretical efficiency should be the same but in the real world it'll be slightly worse (due to threading inefficiency). That said, measuring power draw for the whole system does measure the system's ability to make the most out of its power draw.