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.

  • prev
  • next

Motherboard Support, Test Setup & Benchmarks

Motherboard Support

When the Core 2 Duo was launched Intel tweaked their existing 975 chipset to support the new processor, it was but a quick patch and while 975 based boards did okay with the new CPU at default settings, it wasn’t long before enthusiasts wanted more than stock speeds, here they hit a motherboard limit quickly as the 975 based boards were incapable of reaching high FSB speeds, needed for overclocking. The answer to this problem came in the form of the more affordable P965 chipset, this one was build from the ground up with Core 2 support in mind, and it delivered impressive results. Then came along the first Core 2 Quad processor and enthusiasts were again met with lower than expected FSB overclocks on different motherboards, earlier this year Intel released the P35, an updated mid-range chipset with above average Quad Core support, even overclocking was possible to an extent.

Madshrimps (c)

Madshrimps (c)
QX9650 on the Asus P5K before we updated the BIOS

Back to the QX9650 Quad Core sample we have in the lab today, we first tested the CPU on an Asus P5K motherboard, based on the P35 chipset the BIOS recognized the processor correctly and after a fresh install of Windows XP we were set to start our battery of tests. It didn’t take long for us to find something odd happening; with the CPU running at default speed results were fluctuating between runs, up to 40% in some cases. Only when we disabled Multi Core and ran with a single core the QX9650 acted normally on the P5K board, this was less than ideal of course. Since we already had the latest BIOS the Asus board there was not much else to do than try another board.

Madshrimps (c)

Another Asus board to the rescue, the older P5B Deluxe, based on the P965 chipset this board is know for good Quad Core support, but the latest BIOS did not allow for multiplier changes, so we continued our search for a motherboard which could profit from all the power this QX9650 sample has to offer.

Madshrimps (c)

Our local Computer Shop helped us out by lending a Gigabyte X38 DQ6, this motherboard is brand new, based on the recently released X38 chipset, the Gigabyte board features a 8 phase digital power regulater (PWM) and our overclocking results with the new Quad Core Yorkfield delivered repeatable benchmarks and reached new heights.

Test setup and Benchmarks

Test Setup

Madshrimps (c)
  • Intel Core 2 Quad QX9650 "Yorkfield"
  • Intel Core 2 Duo E6850 "Conroe"
  • Mainboard Gigabyte X38 DQ6 (by
    Video card Jetway HD 2900 XT (by
    Memory 2 * 1024 Mb DDR2 PC7200 EPP OCZ
    Other OCZ 600 watt PSU

  • Hexus PiFast: PiFast is an easy-to-use package written by Xavier Gourdon to compute pi with a very large number of digits. PiFast is avalaible on several platforms, download it from here. PiFast can also compute E and a large family of user defined constants.

  • SiSoftware Sandra 2008: Arithmetic and Multimedia CPU benchmarks.

  • SuperPi Mod v1.5 XS: testing PI calculations which stress co-processor and memory sub-systems. We run 1M and 8M calculations.

  • Wprime : Wprime is a simple, easy to use multithreaded benchmark application that can quickly test your processor performance. In contrary to most other simple benchmark applications, wPrime is written to take full benefit of processors with multiple cores, like the new Intel Core 2 Duo or AMD Athlon 64 X2.

  • 3DMark2001 SE: Discontinued Freeware version, however; this benchmark is still valuable as a tool for testing 3D and memory performance.

  • 3DMark06: Freeware version from Futuremark tests, CPU, Memory and graphics.

    Madshrimps (c)
    3DMark06 CPU Benchmark ~ Multi Core Support

  • MAXON CineBench 9.5: this benchmark stresses the CPU and graphics system primarily using OpenGL.

    Madshrimps (c)
    Cinebench Rendering Benchmark ~ Multi Core Support

  • TechArp X264 bench: Simply put, this test measures how fast your machine can encode a short, DVD quality MPEG-2 video clip into a high-quality x264 video clip.

    Madshrimps (c)
    x264 Encoding Benchmark ~ Multi Core Support

    What's x264, you ask? x264 is a free software library for encoding H.264/MPEG-4 AVC video stream. More info about H.264 can be found here. It's ideal for a benchmark because the application (x264.exe) reports fairly accurate compression results (in frames per second) for each pass of the video encoding process and it uses multi-core processors very efficiently.

  • F.E.A.R. Build-In Benchmark.
  • Cryis Single Player Demo manual run-through, average FPS logged with FRAPS.

    Our first batch of tests has both processors at stock frequency (9x333) and using SPD memory timings (400 Mhz 4-4-4-10).

    • prev
    • next
    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
    Originally Posted by Kougar View Post
    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: 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:

    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.