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M3-ATX possible CPU possibilities?

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  • M3-ATX possible CPU possibilities?

    Hey guys,

    I'm trying to get my CarPC as fast as I can with the possibilities of my M3-ATX. Originally I had the i3-2100T in mind, but now I would like to install 2 webcams which have to record in 720p. For one of them, the 2100T would be enough and I guess the M3-ATX would deal no problem with its power consumption. But since I want 2 now, I guess I need a faster CPU to not get slowed down to a crawl when both streams are being encoded all the time. I had the i5-2500T in mind. But there are no reviews showing how much power it consumes, only the TDP number, which is 10W higher than the one of the 2100T.

    So, do you guys think an M3-ATX will be able to power a complete CarPC (minus optical drive and screen) with an i5-2500T?


  • #2
    TDP = max power draw of the PC. That's what you want to consider for power calculations.

    It might work, but only if you keep from powering anything else off the 12v rail of the M3.
    That means no full-sized HDD.
    That means no powering the LCD from the M3.
    That means an optical drive must be chosen carefully. A full-sized unit is right out.

    The power calculations would be too close for my comfort.

    Good luck.
    Have you looked in the FAQ yet?
    How about the Wiki?

    Under normal circumstances, a signature would go here.


    • #3
      TDP is actually only the maximum heat dissipation value. So it doesnt say that much about the actual power consumption.

      I wont use a fullsized HDD, only an SSD. I also wont use an optical drive nor an LCD powered over the M3. Additionally I am planning to use low voltage RAM (1.25V). However, I was under the impression CPUs use 5V, while the M3-ATX only has 6A on its 5V rail. So USB devices would be more of an issue. My Car PC, incl. the 2 webcams, would have 8 to 10 devices.


      • #4
        TDP represents max power draw in a way that's somewhat goofy.
        The chip manufacturers design the chip to dissipate a certain about of heat. The TDP value is how much voltage the chip can receive that it can effectively dissipate.
        Personally, I think it's a stupid way of representing the power draw of a CPU. I'd much rather see a value for maximum power consumption, labelled as such.

        If you want to see actual real-world power consumption figures, google "i5-2500T power consumption" and follow links to independent reviewers.
        There's a good writeup on XBit Labs.
        Their calculated max power draw under full CPU load? 33.7W. Pretty damn close to the TDP of 35W. Coincidence? I think not.
        Have you looked in the FAQ yet?
        How about the Wiki?

        Under normal circumstances, a signature would go here.


        • #5

          Yeah, it comes pretty close to the TDP of 45W (37.3W), but look at the other CPUs, they are only rarely close to their TDP. The i5-2310 for example, draws only 56.6W and has a TDP of 95W. Or the i3-2100 only drawing 32.3, while having a TDP of 65W.

          Anyway, thanks for the link. But I still cant tell if the M3-ATX would be able to deal with a i5-2500T.


          • #6
            Really? You have all the information you need to figure it out.

            You know the max power draw is about 35W.
            You can look in the manual for the M3 to see how many amps it supplies on the 12v rail. The equation is Watts = Volts X Amps.

            If the max power draw of the CPU is greater than the 12v wattage the M3 can put out, it's a no-go. If CPU draws less, then it's possible.
            If the bigger the difference between the CPU's max draw and the PSU's 12v output, the better.
            Have you looked in the FAQ yet?
            How about the Wiki?

            Under normal circumstances, a signature would go here.


            • #7
              I thought I couldnt, since I didnt know if it was the 5V or 12V rail CPUs use. But your post made me check it again and you were right, CPUs actually use 12V now.
              So based on that, the 12V rail has about 72W and a i5-2500T would draw something like 55W when all cores and the GPU run at 100%, which will most likely never happen in my CarPC. I guess I will try it out then!