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Old 07 January 2011, 18:51   #1455
Join Date: Jun 2010
Location: out in the wild
Posts: 1,250
Originally Posted by Cosmos View Post
>Unless Cosmos made some other hacks?

No !

The SDRam can handle 133 Mhz !

the SD-Ram could only handle such a high frequency if there are enough NOP commands inserted.

The SD-Ram access is:

cycle 1: row-open
cycle 2: column access
cycle 3: NOP (for CL=2)
cycle 4: data take-over and row-close
cycle 5: first possible point for next row-open.

The datasheet clearly states that there must be 20ns space between row-open and column access. The same is true for the time between row-close and the next row-open: This must be 20ns or more.

If you clock faster than 50MHz, then you'd have to do:

1. row-open
2. nop
3. column access
4. nop
5. data take-over & row-close
6. nop
7. first possible point for next row-open.

By overclocking, you are operating the memory out of spec in two critical points. Also, you're moving the phase between memory clock and the command-input. As a result, your computer will not be stable. The CPU might take the overclocking (it's well-cooled), but you're likely to get memory problems.

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