No_Style

ATI will introduce Overdrive 4 with the next Catalyst Driver scheduled in March.

Previously you could only overclock your GPU core with Overdrive, and only by a rather small amount.
Now you can overclock both core and memory and the frequency range will be increased to 75% of the next higher class product.
For example the X800 Non-Pro (400 Mhz / 350 Mhz) could be overclocked up to 456 Mhz Core (400 + (475-400) * 0.75). The memory overclock would be 425 Mhz (350 + (450-350) * 0.75).

This rule does not apply to the XT and XT PE versions of the card and it does not apply across video card generations.

One requirement for Overdrive 4 is that a digitally-signed "SecureBios" is present on the video card. At the moment it is unclear whether current video cards without the signed bios will work. But we think ATI wants to let as many users as possible use the new Overdrive so exceptions will probably be made.

Another requirement is that a thermal sensor circuit MUST be present on all cards supporting Overdrive 4 because temperature monitoring will be used to prevent overheating damage to the chip.
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Source: TechPowerUp

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The_Neon_Cowboy

Actaully memory and core are over clockable and setable with overdrive 3, wich is available but ati made it X850 XT and above only.... just read DH's X850 review and search for the related QA

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Poppi

Baaahh, nothing for the XT PE. Thats OK, I'm happy with my card's performance .

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snake

Well ATI Tray Tool or Rad Linker are not limited like this
I don't see any interest in this overdrive limitations...

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The_Neon_Cowboy

But radlinker and ati try tools aren't 100% warrented, far safer , and supported by ati now are they? They also do not adjust your clocks acording to the cards temps either....

OD3 and 4 whips any third party tools arse

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