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 Post subject: Efika overclocking?
PostPosted: Fri Dec 14, 2007 3:06 am 
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Joined: Tue Nov 02, 2004 2:11 am
Posts: 161
I know I should not ask this...

But I would very much like to know if its possible to overclock the EFIKA. Has someone done this?

Would it be theoretically possible to run the memory not with 133 MHz but with 166MHz and to run the CPU with 500 Mhz instead 400?

Cheers
Gunnar


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 Post subject: Re: Efika overclocking?
PostPosted: Fri Dec 14, 2007 5:16 am 
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Joined: Fri Sep 24, 2004 1:39 am
Posts: 1589
Location: Austin, TX
Quote:
I know I should not ask this...

But I would very much like to know if its possible to overclock the EFIKA. Has someone done this?

Would it be theoretically possible to run the memory not with 133 MHz but with 166MHz and to run the CPU with 500 Mhz instead 400?
No. The CPU is specced at the very VERY maximum to run at 466MHz - this is where you may have gotten an 800+ MIPS number from some old marketing documents - Freescale don't even sell this model and have since revised chip performance to 760 MIPS. I assume it's a core limitation. Certain IP cores in the chip are meant to run at bus speed or a certain fraction. It's all very complicated and intertwined.

This is just how SoC's are; it's not like a plain x86 CPU where you can just bump the frontside bus and watch the CPU clock speed and performance go up as a side effect. For instance if you clocked the 5200B at 466MHz you'd need to pick a new fraction for the peripheral buses, which you would probably end up underclocking. You may not be able to gain a PCI bus clock of a standard rate (although it's possible to run a PCI bus at any clock from 25MHz to 66MHz, a lot of devices may not run at speeds other than 33MHz and 66MHz). The memory bus is running with specific clock rate tied to the spec of the RAM chips. It is not a DIMM and therefore does not have an SPD ROM, so you are at the mercy of whatever chip is on the board, finding the specs of how fast it will run, what the latencies are, and programming them meticulously from some pre-firmware stage (changing them during operation, while code is running, will probably break)

There is by far, too much to take into consideration to make overclocking a pleasant experience, and there is always a trade-off. The Efika is configured, internally, to run at the fastest clocks possible on each peripheral bus, so it's as fast as it can get.

_________________
Matt Sealey


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 Post subject: Re: Efika overclocking?
PostPosted: Fri Dec 14, 2007 7:56 am 
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Joined: Mon Jan 08, 2007 3:40 am
Posts: 195
Location: Pinto, Madrid, Spain
Excellent information!


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