Desktop CPU's vs Mobile CPU's (Conroe vs Merom)

[lunadesign]

Before Conroe was released, I built a MoDT system using a 2.0GHz Core Duo (Yonah) T2500 mobile CPU and the MSI 945GT Speedster motherboard. I was impressed at the performance and the low power consumption compared to my 3.0GHz P4 Northwood. (I know, not a great comparison, but that was my previous system).

I'm about to build a HTPC system and want to build a very quiet, energy efficient system and am wondering if mobile CPU's are still the way to go? Or are the Conroe CPU's sufficiently energy efficient?

If I compare some roughly equivalent Merom and Conroe CPU's I see that the TDP of the Conroe CPU's are almost double the Merom CPU's. For example:

Conroe E6420 2.13GHz 4MB L2 1066MHz FSB LGA 775 = 65W TDP
Merom T7400 2.16GHz 4MB L2 667MHz FSB Socket M = 34W TDP
Merom T7500 2.20GHz 4MB L2 800MHz FSB Socket P = 35W TDP

Of course, I've also noticed:
- TDP's are rough specs
- Conroe CPU's have faster FSB specs
- Merom MoDT motherboards are generally more expensive and there's a limited selection to choose from
- Socket P motherboards are suspiciously non-existent (except in the industrial space) as if Intel is backing away from MoDT
- Apple used the Yonah chips for the first Intel MacMini's but is now using Conroe instead of Merom as I would have expected

I don't have any Conroe systems so I don't have a good reference point for comparisons. I also haven't seen any Conroe vs Merom articles.

What would you guys advise? (And please feel free to share idle/load power specs for your systems if you think they are good examples.)

[nzimmers]

- Apple used the Yonah chips for the first Intel MacMini's but is now using Conroe instead of Merom as I would have expected

I don't have any Conroe systems so I don't have a good reference point for comparisons. I also haven't seen any Conroe vs Merom articles.

Luna, I a pretty sure they started with single core Yonah, then started offering dual core Yohah, and now they use dual core Meroms.... all the mac mini's use mobile chips as far as I know unless they recently switched

just checked, they are still using mobile chips


I think for HTPC use, alot will depend on what kind of grapics requirements you have, I know absolutely nothing about what is needed for things like HDTV etc, so you should look into that.

I think HTPC is quite do-able with a mobile chip - I'm guessing that you could probably get away with an inexpensive mobile CPU, but you would need to make sure your graphics capability are up to the task.

I think the Apple TV has a Yonah in it right?

[jessekopelman]

You've got to give more details on your application. Are you concerned about energy efficiency or just heat? What case are you using? If it as an Anteck NSK2400/Fusion where you can use a decent heatsink the extra heat of an Allendale or Conroe will be no problem (I'd go with an overclocked Allendale over a Conroe any day of the week for this application). Do you really need this kind of horsepower? The new BE23xx AMDs have only a 45W TDP and the AM2 µATX boards have much better feature sets than most LGA775 µATX motherboards. Are you planning to use discrete graphics that can accelerate HD Video? If so those new AMDs will be more than enough. Even without the GPU, the BE2350 is probably good enough, as people have gotten 1080p H.264 to play on the Core Duo based Mac Mini with its GMA950 graphics (1.8 GHz Core Duo == 2.1 GHz Athlon X2). Using a lower TDP chip certainly makes it easier to use a lower profile case, but those slim cases really limit your choses as to drives, cards, and power supplies. So . . .

[Mikael]

The easiest route may be to get a Conroe CPU and the undervolt it. For example, my E6600 in a Gigabyte GA-965P-DS3 was able to undervolt to 1.0V at the stock frequency of 2.4GHz. This likely puts the CPU at close to 30W under full load, which is pretty good when considering the performance.

Not all Conroes may be as undervoltable as mine, but you should be able to get close.

[jaganath]

power consumption of latest Core 2 (E2140/60) is much lower, plus greater choice of MB.

[autoboy]

IMHO, MoDT is dead because desktop CPUs have adopted the mobile features.

For HTPC applications I would have to recomend the ease of use, and low cost of AMD chips. The onboard graphics solutions for AMD are much more mature than the Intel solutions, the 45W AMD CPUs are easy to just pop in, CnQ is more efficient than Intel Speedstep, and raw performance is not as big of an issue with HTPCs.

If you are planning on running BluRay or HD-DVD, you might look into a powerful CPU, but I recomend you stay away from it on the desktop for now. Also remember that Phenom CPUs are going to be backwards compatible with AM2 boards and low clock AMD CPUs are so cheap now that you can basically just throw them out when you find you need more power. A 1.9ghz dual core CPU is more than enough for everything but high bitrate 1080p h264.

If you ARE going to go with Intel, then you can undervolt some of the low clock Core 2 chips and get good low power performance for low cost. I would think that this is better than MoDT.

[lunadesign]

Luna, I a pretty sure they started with single core Yonah, then started offering dual core Yohah, and now they use dual core Meroms.... all the mac mini's use mobile chips as far as I know unless they recently switched

just checked, they are still using mobile chips

I think for HTPC use, alot will depend on what kind of grapics requirements you have, I know absolutely nothing about what is needed for things like HDTV etc, so you should look into that.

I think HTPC is quite do-able with a mobile chip - I'm guessing that you could probably get away with an inexpensive mobile CPU, but you would need to make sure your graphics capability are up to the task.

I think the Apple TV has a Yonah in it right?

Yep, I was wrong. The Mac Mini's are using Merom. So there must be some sort of advantage to using the Merom over Conroe.

According to Wikipedia, Apple TV has a 1.0GHz Pentium M, code-named "Crofton".

[lunadesign]

You've got to give more details on your application. Are you concerned about energy efficiency or just heat? What case are you using? If it as an Anteck NSK2400/Fusion where you can use a decent heatsink the extra heat of an Allendale or Conroe will be no problem (I'd go with an overclocked Allendale over a Conroe any day of the week for this application). Do you really need this kind of horsepower? The new BE23xx AMDs have only a 45W TDP and the AM2 µATX boards have much better feature sets than most LGA775 µATX motherboards. Are you planning to use discrete graphics that can accelerate HD Video? If so those new AMDs will be more than enough. Even without the GPU, the BE2350 is probably good enough, as people have gotten 1080p H.264 to play on the Core Duo based Mac Mini with its GMA950 graphics (1.8 GHz Core Duo == 2.1 GHz Athlon X2). Using a lower TDP chip certainly makes it easier to use a lower profile case, but those slim cases really limit your choses as to drives, cards, and power supplies. So . . .

Thanks for the questions. I'm fairly early on in building this box, but my concerns are both energy (want to leave this on all the time) and heat (the box is going to be located in a cabinet with so-so ventilation). Case wise, I'd ideally like to get one with a touch-screen LCD (like the Zalman HD160XT) so I can select music without having to turn on the TV. I'll be connecting to a 62" 1080p DLP TV. Would prefer to use the onboard graphics but may end up using a separate PCI-e graphics card with just enough oomph to get the job done.

[lunadesign]

The easiest route may be to get a Conroe CPU and the undervolt it. For example, my E6600 in a Gigabyte GA-965P-DS3 was able to undervolt to 1.0V at the stock frequency of 2.4GHz. This likely puts the CPU at close to 30W under full load, which is pretty good when considering the performance.

Not all Conroes may be as undervoltable as mine, but you should be able to get close.

Have you tried measuring the system power with a power meter? How did you come up with your 30W number?

[lunadesign]

power consumption of latest Core 2 (E2140/60) is much lower, plus greater choice of MB.

I thought these were also listed with a TDP of 65W?

[jaganath]

TDP does not = power consumption. look at, for example http://www.digit-life.com/articles2/cpu ... page3.html

their idle number for the BE-2350 looks too high and the 100% load figure for the E21X0 looks unbelievably low but apart from that that chart gives you an idea of how power consumption can vary among chips with the same TDP. typically only the fastest model in a range will meet or exceed the TDP in normal use. other tests show the E21X0 within a couple of watts of the AMD low-power BE- range.

[lunadesign]

TDP does not = power consumption. look at, for example http://www.digit-life.com/articles2/cpu ... page3.html

I always figured as much but this chart really hits it home. Thanks!

What's also interesting is that the E4400 has the same power consumption at idle and only 4 more Watts than the E2160 at 100% load.

I'd love to see a similar chart with a few Merom's thrown in.

[Mikael]

Have you tried measuring the system power with a power meter? How did you come up with your 30W number?

Yeah, I've measured my system power consumption, but that's not the data I used to come to my 30W figure. There are a couple of sites that have measured the actual power to the CPU (like Xbitlabs) and from those tests, the E6600 seems to consume around 50W. If you take that number and multiply it by (1/1.27)^2, you get 31W. 1.27V is the stock voltage, or close to it, of most E6600.

[jessekopelman]

Thanks for the questions. I'm fairly early on in building this box, but my concerns are both energy (want to leave this on all the time) and heat (the box is going to be located in a cabinet with so-so ventilation). Case wise, I'd ideally like to get one with a touch-screen LCD (like the Zalman HD160XT) so I can select music without having to turn on the TV. I'll be connecting to a 62" 1080p DLP TV. Would prefer to use the onboard graphics but may end up using a separate PCI-e graphics card with just enough oomph to get the job done.

If I were to use that case (Zalman HD160XT) and I were running some version of Windows as my OS, I think I'd go with an Intel E4400 coupled with an Abit Fatal1ty F-I90HD motherboard and Mini Ninja heatsink. The nice thing about the E4400 is that you can easily overclock it to 3GHz without increasing the voltage (thus with only negligible impact on heat and power consumption). The 690G chipset on this board is pretty low consumption for a desktop board and the E4400 idle draw is very low. Undervolting might help power consumption, although using a very high efficiency PSU might help even more.

[jojo4u]

Inefficient chipset and motherboard design are killing Conroe's power consumption at the moment. You either needs MoD Intel or desktop AMD.[1] Power-consumption should be equal, but Intel costs more. You should keep an eye on HD playback of the integrated solutions since external is always bad regarding power consumption
Btw, a 690G (without "wonder" BIOS) and a 6000+ was not enough for smooth 1080p because of the AACS overhead.[2] Intel integrated has no HDMI, so watch out for the new BIOS.

[1]
viewtopic.php?p=361693#361693
viewtopic.php?p=364187#364187

[2]
http://anandtech.com/talkarticle.aspx?f ... frmWhere=2 (search for Jojo4u)
2nd test: http://translate.google.com/translate?u ... uage_tools (decoding CPU only)

[jessekopelman]

You should keep an eye on HD playback of the integrated solutions since external is always bad regarding power consumption
Btw, a 690G (without "wonder" BIOS) and a 6000+ was not enough for smooth 1080p because of the AACS overhead.[2]

As you noted, this is less of an issue with Intel CPU.

Intel integrated has no HDMI, so watch out for the new BIOS.

That's why you use the Abit Fatal1ty F-I90HD -- fairly efficient 690G chipset, support for Intel, and it has HDMI!

[jojo4u]

Btw, a 690G (without "wonder" BIOS) and a 6000+ was not enough for smooth 1080p because of the AACS overhead.[2]

As you noted, this is less of an issue with Intel CPU.

A new test: a Geforce 7050 has PureVideo and allows fluent pictures with a 5200+, but not a 4800+. ( C't 18/07, page 147).
Thanks for the pointer to the Abit board! I forgot about it :/

[EFoppen]

I have both a 945GT Speedster A4R with T7200 (as main desktop) and a Asus MA2-VM HDMI with X2 3800+ (as HTPC). Both running on the same fanless ST30NF power supply. Both computers run Vista. Only since very recently I am able to use the integrated video from the Speedster, before it would output to the non existent laptop display. I have always used the onboard graphics of the MA2-VM.

The Intel config is taking approx 60Watt in idle mode (on integrated graphics), the AMD does approx 75watt (but is running one more slow running case fan). I bet the graphics performance of the 690G chipset is better. The price of the Intel is so high that I would never do it again, but at the time I built it, the 690G did not yet exist. For the price of the Speedster motherboard alone, you can get the AMD CPU plus the Asus MA2-VM. Also not helpful is the very noisy non-standard CPU cooler on the T7200. I agree the Intel MoDT config requires slightly less power, but you need to run it 24/7 for 8 years (where I live) to break even.

[merlin]

If I didn't use a high power discrete graphics card I think I'd get some pretty low idle wattage on my system. As it is, a conroe running at 1.0v will have an extremely low wattage. I think merom is completely unneccessary. The bigger issue is to avoid motherboards with a large amount of power waste and also get one with undervolting features. I was looking at about 120w idle for my total system including psu efficiency loss and high end discrete with my conroe at .95v.

[nzimmers]

I have both a 945GT Speedster A4R with T7200 (as main desktop) and a Asus MA2-VM HDMI with X2 3800+ (as HTPC). Both running on the same fanless ST30NF power supply. Both computers run Vista. Only since very recently I am able to use the integrated video from the Speedster, before it would output to the non existent laptop display. I have always used the onboard graphics of the MA2-VM.

The Intel config is taking approx 60Watt in idle mode (on integrated graphics), the AMD does approx 75watt (but is running one more slow running case fan). I bet the graphics performance of the 690G chipset is better. The price of the Intel is so high that I would never do it again, but at the time I built it, the 690G did not yet exist. For the price of the Speedster motherboard alone, you can get the AMD CPU plus the Asus MA2-VM. Also not helpful is the very noisy non-standard CPU cooler on the T7200. I agree the Intel MoDT config requires slightly less power, but you need to run it 24/7 for 8 years (where I live) to break even.

When I tested out the 945GT speedster, I was getting 48W at full load with a single core yonah + notebook drive + 1 GB ram

I think a second core will add 10watts and a normal HDD will definately bring bring up the power requirements.


I think the advantage of using a mobile intel chip really stems from if/where you can buy a cheap one. If a yonah or a core duo will work a used one might be $20-50, merom will be higher

[GnatGoSplat]

I have both a 945GT Speedster A4R with T7200 (as main desktop) and a Asus MA2-VM HDMI with X2 3800+ (as HTPC). Both running on the same fanless ST30NF power supply. Both computers run Vista. Only since very recently I am able to use the integrated video from the Speedster, before it would output to the non existent laptop display. I have always used the onboard graphics of the MA2-VM.

The Intel config is taking approx 60Watt in idle mode (on integrated graphics), the AMD does approx 75watt (but is running one more slow running case fan). I bet the graphics performance of the 690G chipset is better. The price of the Intel is so high that I would never do it again, but at the time I built it, the 690G did not yet exist. For the price of the Speedster motherboard alone, you can get the AMD CPU plus the Asus MA2-VM. Also not helpful is the very noisy non-standard CPU cooler on the T7200. I agree the Intel MoDT config requires slightly less power, but you need to run it 24/7 for 8 years (where I live) to break even.

Very strange thing, but the graphics performance of the old GMA950 seems to be a LOT better in my experience. I can't explain it myself.
I tried a 1080i HDTV recording from Media Center 2005, copied it to my wife's Vista laptop (945GM w/GMA950 onboard video). At 1280x800 resolution (letterboxed to 1280x720), the laptop played the video smoothly and flawlessly. It only has a 1.73GHz Celeron M (Yonah)! I attempted to duplicate this with a desktop motherboard so I got an MSI Speedster A4R and a Celeron M 520 1.6GHz (Merom). To an output resolution of 1280x1024 (letterboxed to 1280x720), the same video played flawlessly! On my Gigabyte GA-MA69G-S3H 690G with a 2.3GHz Athlon X2 4400+, the SAME video using Vista Media Center would play with slightly reduced framerates and choppiness in certain spots to an output resolution of 1280x720. I even tried MCE 2005 instead of Vista, the AVIVO decoder, Cyberlink decoder, nVidia PureVideo... I was never able to match the performance of the GMA950. Maybe I'm doing something wrong? With Catalyst 7.8 drivers, I get a Windows Experience rating of 3.0 for desktop, 3.3 for gaming. The GMA 950 gets 3.1 for desktop, 3.2 for gaming. I never thought of the GMA950 as a fast IGP, but it really surprised me.

My Speedster A4R idles at 45W, at 100% CPU load at 57W, and CPU+disk activity I saw a brief random peak of 63W. This is with a laptop drive, desktop DVD-ROM drive, and using a crappy 7-year old POWMAX 400W psu measured by a Kill-A-Watt.

[jojo4u]

On my Gigabyte GA-MA69G-S3H 690G with a 2.3GHz Athlon X2 4400+, the SAME video using Vista Media Center would play with slightly reduced framerates and choppiness in certain spots to an output resolution of 1280x720.

Is this with AACS? Otherwise, perhaps the deinterlacing is to blame.

[GnatGoSplat]

On my Gigabyte GA-MA69G-S3H 690G with a 2.3GHz Athlon X2 4400+, the SAME video using Vista Media Center would play with slightly reduced framerates and choppiness in certain spots to an output resolution of 1280x720.

Is this with AACS? Otherwise, perhaps the deinterlacing is to blame.

No, no AACS. This is just a 1080i video recorded from a CBS OTA HDTV broadcast.
It's possible it could be deinterlacing, but I did try every deinterlacing option in the Catalyst 7.8 menu including "Weave (no deinterlacing)" and toggling pulldown off and on with very little improvement.

[david25]

Hi, I use the following

Asus N4L-VM DH MB
T7200 2.13Ghz CPU
Nvidia 8600GTS
160GB HD
2 x Optical
4 x 80mm fans

The whole system idles around 65watts, with non-gpu accelerated HD at 80.

I'm swapping the 3.5" HD for a 2.5", so will idle drop to 60watts (measured at the wall)

Merom MB prices have declined in the UK, the asus is now $200, I've seen the expensive aopen boards on ebay for $70 (new!)

Merom setup are still be best for power consumption, unless you choose a laptop (my L2400 IBM uses around 12watts with the lcd)

[GnatGoSplat]

Merom MB prices have declined in the UK, the asus is now $200, I've seen the expensive aopen boards on ebay for $70 (new!)

I just checked eBay and found the one I think you were talking about, went for $61+S&H? I wish I'd known about that one, I would have greatly preferred that over the MSI Speedster A4R I ended up buying because I have an abundance of spare DDR2 SODIMMs!

[david25]

Merom MB prices have declined in the UK, the asus is now $200, I've seen the expensive aopen boards on ebay for $70 (new!)

I just checked eBay and found the one I think you were talking about, went for $61+S&H? I wish I'd known about that one, I would have greatly preferred that over the MSI Speedster A4R I ended up buying because I have an abundance of spare DDR2 SODIMMs!

Yes, these are the ones, normally around $350 a great buy!