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Which CPU / Motherboard for cool-running HTPC?

Discussion in 'Computer Components' started by John_N, Jun 18, 2003.

  1. John_N

    John_N
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    Hi Guys

    I'm about to re-build my athlon HTPC using new components and move it into the same room rather than next door.

    I've decided that intel components run a lot cooler hence quieter.

    My question is around CPU spec that I need.

    SHould I go for the P4 2.6 with HT or is this too much power? would I be better off with a cereron 2.0ghz?
    Would this do the job? Or would I be better off with the P4 but UNDERCLOCKING it?

    I'm thinking of either the Zalman copper flower cooler or the Thermalright SK-900U just for the sheer size of cooler. I would prefer to cool the CPU passively - just using one papst case fan to shift air through the case if necessary. Let's ignore the PSU fan for the time being because it's going to be the 200W PSU included in the DIGN HV5 HTPC case and I don't know how quiet it will be.

    Has anyone tried running a P4 fanless?
    Does anyone run a celeron fanless?
    Will a celeron be enough?
    Will the 200W PSU be enough????

    oh - and if anyone knows of an especially quiet DVD-writer then that would be cool as well...
    Intended config:

    CPU + motherboard
    Seagate Barracuda V 120GB
    Nebula Digi-TV PCI card
    EIDE DVD writer
    Radeon 9000 pro fanless
    512MB RAM.

    Thanks
    John

    ---My current system--

    My current HTPC runs;

    Theatertek DVD player
    Nebula Digi-TV card - used as personal video recorder and tuner.
    musicmatch MP3 player
    Girder
    ATI remote wonder

    and I'm thinking of using two digi-TV cards to give me true record-one-channel whilst watching another channel capability.

    My current HTPC uses an Athlon XP1800+ and is fine.
     
  2. gab2001uk

    gab2001uk
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    Hi

    I have built mine using a P4 2.4GHz witth copper flower cooler and Zalman fan running at half speed, and quiet PSU. This setup is still noisier than an older Athlon 1.2 GHz setup with a radial cpu cooler, and standard PSU, but I needed the processing power for some DVD processing actions. If it were not for this I would stick with the Athlon for HTPC use

    I did try the cooler without a fan, but the temperature got too high after a few minutes, so would not recommend it.

    You may have a problem with dual Digi-TV cards. It uses overlays, and only one overlay is possible at a time. Trying to run DigiTV and Vidac VMagic at the same time complains about it and refuses to run. Email Nebula first to see if it can be done, they are very good with this type of enquiry.

    I have the Sony DW-U10 DVD re-writer which reads / writes all formats except DVD-RAM, ( http://www.bigpockets.co.uk/results...fers&session=8ecb213b1fe796e8a6bbf6129c1fd795 ) and a separate DVD-ROM to use as a player/ on-the-fly DVD copier. There is a utility to cache/quieten the DVD drive from http://www.dvdidle.com which should run any DVD quietly.
     
  3. John_N

    John_N
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    Hi

    Thanks for the reply. I'm very surprised because I thought that the athlon had a higher power dissapation than the P4 in terms of W heat generated, especially the older thunderbird and palomino athlons.

    What about the celeron anyone? I gather that the 2.0ghz S478 celeron doesn't generate much heat? Does a 2.0ghz celeron work as well in a HTPC as an athlon 1800XP? does the smaller cache matter in HTPC applications?

    I could use it with a Thermalright SK900 copper heatsink, or a zalman 6500 copper flower or a zalman 7000 copper. I don't care. All I want is it to be quiet and have a reasonable amount of CPU power - say equivalent to an athlon XP1800 (present machine) for sake of argument.

    I don't need to do any DVD crunching because I've got a server upstairs to do that.

    It just needs to play DVD from hard disk (ISO) and from the drive and run nebula digi-TV. I'm not a gamer but it would be quite nice if it could run quake 3 occasionally.
     
  4. John_N

    John_N
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    Cmon someone.... Someone must have a view on which CPU is best for cooler and quieter operation and still fast enough...

    Celeron
    P4

    or
    athlon - although to be honest Iwould be surprised given the athlon's reputation for running hot & the power dissapation figures...
     
  5. james.miller

    james.miller
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    absolute coolest out of the two would be the p4 celly and zalmans bigest and badest cooler (i forget the name - 700cu or something similar).

    id rather go athlon myself though (xp1700+ to be exact) - much cheaper and better value. if you do, get an slk-800. dont bother with the 900 the difference is literally 1-2c which i dont think is worth the extra money. So get the slk-800, and a panaflow L1A fan and your set.
     
  6. rhinoman

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    If your going to use the Nebula DTV solution instead of Dscaler then I dont suppose that horsepower is very important so probably anything will do. I'd go cheap athlon with an Nforce board...epox 8rda gets good comments, SLK800 is very hard to beat.
     
  7. John_N

    John_N
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    Thanks for the advice.

    Surely not possible to run an Athlon fanless even with a BIG heatsink... is it??

    The quest for a silent HTPC was leading me towards the coolest solution if only for the possibiility of using a big heatsink and a quiet fan to get air running through the case only.. ie no heatsink fan for the cpu.

    I think the newer Barton athlon cores are supposed to run cooler than the palomino which in turn runs cooler than the thunderbird but even so, does this make the athlon a contender in the fanless stakes?
     
  8. rhinoman

    rhinoman
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    John,

    How close will the HTPC be to you when its in your lounge? Is the HS10 in the room with you?

    Do yopu think perhaps that your getting a bit hung up on absolute silence when actually near silence will do:(

    My HTPC with a xp2100+ (thunderbird) with a slk800 and a 92mm fan on it, no case fans and a seisonic ss300 PSU (which is now beaten in the noise stakes) is barly audible at 1m away, you need to put your hand over the psu vent to know that its on when the PJ is running at the other end of the room. If I got a quieter PJ then it might become a little more relevent but its definitly not at the moment.:)
     
  9. Mr. Wilby

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    John,

    I'm using:

    - LMP case
    - Abit NF7S nForce 2 motherboard
    - SLK800
    - XP2100+ (over clocked)
    - a very very quiet pabst (or is it panaflow - I can't actually remember which one I opted for) 9cm fan.
    - ATI 7500 (no fan)

    The loudest part of my setup is now the northbridge fan on the motherboard. I have a zalman northbridge heatsink but I've yet to fit this.

    The SLK + a large, quiet fan go really well together and do make for a quiet machine.

    Worth considering and far cheaper than the P4 route.
     
  10. John_N

    John_N
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    Ok Thanks. I've looked at the specs for the "Barton" core and it seems that the power dissipation is around 69W I think. This compares with the P4 which had higher than expected power dissipation.

    So I'm tempted to try an Athlon XP2500+ (Barton) and an NForce2 motherboard, a BIG cooler, and then experiment with underclocking and undervolting the CPU because I don't need that level of performance - XP1700 type performance will do just fine.

    The HTPC will be in the same room as the HS10. It will be further away from me than the HS10.... However, I'm looking to use a plasma screen with it as well (ie HS10 over DVI, plasma over VGA) and hence long-term quietness is still an issue.

    The unit will be 2 metres from my ears.

    J
     
  11. james.miller

    james.miller
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    i really cant recommend the 2500 due to its price. you can easily get 2500+ performance out of a 1700+....and a heck of a lot more. If your going to get the fastest most overclockable chipset and the best cooler, you might aswell get the best overclocking cpu, and that is the 1700+ without a doubt.
     
  12. John_N

    John_N
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    Hi James

    Yes I realise that, but I'm not interested in overclocking. The cost doesn't matter to me - I'm interested in building the quietest home cinema PC I can manage that will still do the job.

    I used to be into overclocking and even went to the lengths of dismantling an old Kryotech Super G to supercool my athlon to minus 50 celcius but to be honest I lost interest. And besides I kind of got fed up of the computer sounding like a furnace with all those fans.

    This makes interesting viewing:

    http://www.tomshardware.com/cpu/20030217/images/cpu_chart.gif

    This is the power dissipation figures of all the CPU cores for different frequencies. The same toms hardware review also gives comparative performance which kind of seems to rule out the celeron because of it's tiny cache which has a bit hit on performance.

    However, the "barton" core (AMD) does have relatively high power dissipation compared to the P4 Northwood so I'm still wondering about spending the extra and going for intel if I'm going to be running fanless.

    Yes I know AMD is cheaper. The PC will be about £100 - £150 cheaper using AMD but that's no good if it's going to be too loud... Still thinking.

    Thanks for the input Mr Wilby & John S by the way. Good to hear that you have both Athlon systems that you are happy with.

    Sitting on my cheque book for a bit longer...
     
  13. loonatic

    loonatic
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    I am currently using an P4 2.6 with a Zalman 7000Cu Copper cooler complete with variable fan speed controller in a custom built case with a Zalman 400w Silent PSU along with two 80mm intake fans at the front and two 60mm exhaust fans at the rear all running at a smidge over 5v to prevent them stalling.

    I have installed the Zalman ZM-80A heatpipe heatsink on my Radeon 9700 non-pro and the ABIT IT7MAX-2 motherboard does not have a fan on it's southbridge and has an optical out at the rear.

    The end result is that from a few feet away it is damn near silent. You can hear the hard drive occasionally - which is a fluid bearing Maxtor 120GB. The DVD rom still makes a racket but I've got into the habit of ripping the DVD to an ISO file first and having TheatreTek play it back of the HDD.

    If you'd like any other details feel free to ask away.

    Cheers, Lee

    PS: No I don;t work for Zalman :laugh:
     
  14. Caveat

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    "quietest home cinema PC I can manage that will still do the job"

    This depends on how demanding the job is. What looks good on a big TV might not look so good with a projector.

    You could make a totally silent, fanless solution, using a VIA C3 chip and do the DVD / video in hardware (XCard etc) or use the EPIA MoBo - effectively this setup in one mobo.

    Once youre down at these power levels you can even get fanless power supplies and the loudest component would be the HD - use a CE Memory card drive and, if your source is on a network drive, even this could go!

    Or you could just turn it up a bit .... go on ... a bit louder
     
  15. John_N

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    Hi
    My current XP1800+ HTPC is connected via DVI to a Sony HS10 projector with an 84" screen in my viewing room. It provides enough performance to watch TV via nebula and watch DVD via Theatertek. The machine must also be able to record digiTV onto the hard drive and function as a PVR without dropping frames.
    That's really all I want from it. If it can be faster and still be quiet, then fine. But the above is the minimum it must support. I have therefore ruled out the VIA offering as not being powerful enough. Performance round about Athlon XP1800+ seems to be OK.

    Hi Loonatic
    Why have you got so many fans?

    My HTPC is likely to be;
    CPU + motherboard + zalman copper cooler
    as quiet PSU as I can manage. I even thought about the fanless ones but let's wait and see.
    nebula digitv card
    radeon 9000 pro (fanless) card.
    This is going to be in an LMP case or in a DIGN HV5 case depending on whether lMP bring a tray loader out or not.
    I was hoping to be able to get away with 1 quiet 80/92 mm case fan, rear mounted, blowing air out of the case.
    I was thnking of underclocking and undervolting the CPU to make it run slower and cooler.
    DVD drive racket is another issue. I wanted a DVD writer and obviously as quiet as possible. I may experiment with rubber mounting and sound insulation with the unit that I get, because I imagine that a lot of the sound is due to vibration of spinning disk. I would also imagine that utilities to slow down the speed would be quite effective.
     
  16. John_N

    John_N
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    Oh - Mr Wilby:

    How many fans are in your system? IS the 92mm fan mounted on the heatsink or in the case? I was wondering whether the thermalright would work with no fan mounted on it and a big case fan sucking air out of the case..... I get the impression that the zalman cooler might work better in that scenario.. any ideas?
     
  17. John_N

    John_N
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    After a bit more digging around I found out the following figures for heat dissipation:

    P4 2.4 "Northwood" = 57.8W
    P4 2.53 "Northwood" = 59.3W
    P4 2.8 "Northwood" = 68.4W

    Athlon XP2800+ "Thoroughbred 'B' " = 74.3W
    Athlon "Palomino" 1600mhz = 67.5W

    Given that a zalman flower has a thermal capacity of approx 0.5 degrees C / W with the fan in "slow" mode and a much worse and unmeasured thermal capacity the less cooling you give it, I'm inclined to think that the 10W - 15W power differences are going to give temperature differences of about 7-10 degrees above ambient.

    Hmm. So there you have it. P4 runs cooler but more expensive.

    You pays your money & takes your choice I suppose. :)

    J
     
  18. Caveat

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    From Intels spec sheet:
    http://www.intel.com/design/pentium4/datashts/29864310.pdf

    The P4 2.8 has a max temp of 75 C.
    I imagine running it at this temp shortens its life considerably, but your expected life for it is probably a fraction of its specified life anyway.

    I believe that cooling is a function of the temp difference ie:
    (cpu temp)cubed - (ambient air temp)squared
    (someone who *knows* please correct me)
    In which case the hotter the cpu the more W your heatsink shifts for the same ambient temp - maybe running at these temps is possible without a fan?

    Ive used poweramps for years that had output devices that were too hot to touch, so its certainly possible to run electronics at these temps.

    Im not advocating running your cpu at these temps, just thinking outloud.
     
  19. John_N

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    simple conductive thermal heat flow through any medium is proportional to the difference in temperatures.

    ie flow through a bar is proportional to the temp difference between the ends.

    This means that a heatsink loses more energy per unit time the hotter it is, just like the temperature of any cooling body is not a straight line but an exponential curve.

    In our "fanless heatsink" scenario, the temperature of the CPU will therefore increase until such a time as the temp difference between ambient and the CPU is so great that the flow of heat away from the CPU will equal the power dissipation of the CPU.

    How high this figure is, depends on the so called "thermal resistance" of the system.

    Unfortunately our operating temp is limited by the max operating temp of the silicon junctions in the CPU. The absolute max operating temp for a silicon junction is about 185 degrees C but the junction will most likely be destroyed by electron migration before that temperature. The casing may also be damaged.
    This problem tends to increase as gate size and junction sizes decrease. Power devices in amplifiers have a safe operating temperature much higher than a CPU because this is just one transistor (in the case of a FET or BJT) or just a few transistors (in the case of an amp IC). The physical size of the transistor is much larger and this makes is less suesceptible to damage via electron migration and other mechanisms and allows it to operate hotter for longer.

    This means that unfortunately, when intel or AMD specify a max junction temperature for the CPU core of about 90 dgrees C, they really do mean it. Running a CPU at this temp is likely to destroy it reasonably quickly. I think the rule of thumb is that your CPU half-life doubles for each 10 degree drop in temperature, to give you an idea.

    Hence, for fanless operation we need;

    CPU with lowest possible power dissipation
    Heatsink and surrounding air (the thermal system) to have the lowest possible thermal resistance that we can manage.

    This will probably be accomplished by using a P4 2.4, underclocking and undervolting it, and using a copper heatsink with a large surface area that lends itself to natural convection cooling. Obviously some designs are better than others. Some heatsinks are designed for forced air cooling and work very poorly in a convection situation. Also, most computer cases are no really designed for passive cooling. Even the cases that look like AV gear like the LMP case or the DIGN case do not have ventilation holes in the top and bottom - which you obviously get in a passively cooled power amp. I would imagine the thermal performance of a HTPC would be improved significantly just by using a cash with mesh sides.

    An interesting topic though.. Still haven't bought anything..:)

    J
     
  20. John_N

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    Stop press!
    I've just read the AMD spec sheet for the Athlon XP series 8 and 10 ships and it makes intresting reading;

    http://www.amd.com/us-en/assets/content_type/white_papers_and_tech_docs/25175.pdf

    Here we have the figures that for an Athlon XP revision 8 chip (thoroughbred core I believe) we have;

    Clock = 1533mhz (1800+) Pmax = 51.0W Ptyp = 44.9W

    IF we are using a "Barton" core, this rises to 68.3W max 53.7W typ

    For a P4 (533 FSB) we have 59.8W for 2.4 and 68.4W for 2.8

    I take back my previous remarks on the P4. I've experimented with this Athlon system over the last few days and I've managed to "underclock " it and reduce Vcore to 1.575v and run it with an old thermalright cooler with a 5v cpu fan.

    Hence I'm back on the Athlon track again.

    I think I'll get a "thoroughbred" XP 1800+ and a massive heatsink and we'll see..

    J
     
  21. james.miller

    james.miller
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    the 2500 runs at 1.8ghz - right now my xp1700 is running at 1.9ghz with just an slk-800 heatsink and a 2200rpm fan, and it's never hit 50c under full load.
     
  22. John_N

    John_N
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    Hi James
    Is that with an FSB overclock or changing the multiplier?

    Like I said, back on the Athlon bandwagon again.

    I'm still wondering which is the better heatsink for quiet or passive operation - Zalman 6000 copper flower or the thermalright SLK800 / SLK900 . Mind you - it won't be a disaster if I end up buying both of them.

    In my ideal system I would be using one 92mm fan as a combined case fan and CPU cooler.
     
  23. james.miller

    james.miller
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    both. it is running at 200mhz x 9.5. the board its self should be capable of >220mhz but i have tried yet. it will allow any combination of fsb and multiplier on my 1700 t/bred.

    the slk is definatly the better heatsink. the only zalman that out-does them is the 9000 - but thats a p4 only 'sink at the moment.
     

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