Clock Speed of U740?

HiFive Unmatched
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What is the clock speed of U740?

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In Q&A at the Linley conference presentation Yunsup Lee said the FU740 on the boards being sold now is 1.4 GHz official, but individual chips might be ok faster. https://www.youtube.com/watch?v=11h7Pnfgsn0#t=17m

I don’t know whether that means it boots at 1.4. The old HiFive Unleashed boots at 1.0 GHz and I bet many people leave it at that. Mine seems to run ok at 1.5 but if I work it hard for several hours programs start crashing. It’s fine for months on end at 1.4.

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We haven’t released clock speed info yet as far as I know.

Yunsup is talking about the HiFive Unleashed board when he mentioned 1.4GHz. He then says that the Unmatched will be same speed or higher, but does not actually say what the clock speed of the Unmatched is.

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You’re right.

I’m guessing the shuttle run test chips didn’t run as fast as hoped and everyone is waiting for the next batch to see. It’s going to be disappointing, given the pipeline changes, if they can’t do around 2 GHz like the A55s in the Odroid C4 and other similar boards.

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Could you please help me to find the maximum temperature for FU740-C000 at this speed?

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I’d suggest new threads for new questions. You didn’t mention a clock speed but I doubt that max operating temp depends on clock speed. It probably runs hotter at a higher speed, but that doesn’t change max operating temp. We don’t publish detailed info for the FU74-C000 as we don’t sell the chips, but the board datasheet under non-operating conditions says 70C. The sensors command can be used to see the current temperature of the board and chip, and possibly also add on boards if they have temp sensors also. Running sensors on my idle board at 1.2GHz says

CPU Temp:     +37.0 C  (low  =  +0.0 C, high = +85.0 C)
                       (crit = +85.0 C, hyst = +75.0 C)

The PWM driver is set up to shutdown the CPU if it gets too hot, though I’m not sure of the exact temperature. I would advise against running the chip too hot as that risks ruining an expensive board.

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Fair enough, thanks a lot, Lim!

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Jim!

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There was a brief internal discussion about this thread, with some clarifications. Here are my notes:

  • We concluded during testing that the maximum operating temperature of this part should be 85°C. We concluded that with the fan integrated, it should never reach this temperature.
  • We do not sell the FU740 chip separately from the board/fan/etc.
  • It’s the TMP451 thermal monitor chip that’s programmed to shut the chip down, not the PWM
  • The “non-operating conditions” is for the board not the chip. As long as the ambient temperature is kept within what’s mentioned in the datasheet, the FU740 will remain within the operating spec
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