Wanting to OC my sapphire HD4870...

[OJay]

Hey guys,

I've gotten my HD4870 from its stock 750/900 MHz to 830/1000 MHz stock volts / cooling so far. I am using ATI Tray Tools. Any higher than 830 on the core and games start crashing, so I figured I might up the volt s a bit to make it more stable, so i push em up from 1.263 to 1.276 on the core and go 840 Mhs/1000Mhz and games still crash... my temperatures are being kept low (wont exceed 75 C) as Im using a custom fan profile which can get to the fan up to 100% funtionality if my temp exceeds 80. I have a Gigabyte ODIN 800W PSU. Is that solid enough for a big OC or no?

My target is to push it to 850Mhz on the core. But I do not want to do a BIOS flash. Could my PSU be limiting me btw?

 

[Ben90]

no

 

[OJay]

so im being limited by the PSU or is it just my card? But this is a quality PSU and my card is suitably provided by the 2 x pin power connectors it needed.. where does this PSU exactly lack? the amerage on the 12 rail? keep in mind that my card can go up to 852 Mhz on the core using the Ati Tray Tools artifact test. But it crashes in games.

 

[Ben90]

oh sorry didn't see you had two questions
your power supply is fine.

 

[OJay]

Ok then. Why is the card still unstable even if I crank up the voltage to 1.276v? I mean I do 830 stock volts stable. So it's reasonable to assume that 1.276v would at least gimme 20 extra Mhz stable...

 

[CrystalBay]

Because the components on that 4870 are stock and not designed to hit high clocks. If you manage 850 I doubt the card will live very long.

good luckD:

 

[SlowSpyder]

4870's were never stellar overclockers. I think ~10% was the norm, most of them seemed to settle somewhere around 790MHz on the low end, on the high end they'd max out CCC at 820MHz. You can push the voltage some, but I wouldn't expect huge gains. I've heard of some high clocks, but if I were you I'd probably be happy at 830MHz. I think the curve of how much voltage you need to how much extra clock speed you get ramps up pretty quick on the 4870.

 

[OJay]

Ok... tiny update,
there is a feature in ATT where I can add in a custom core voltage in addition to the ones preset. Ones available for the 4870 are 1.25, 1.263, 1.267, i figured i add a 1.289v but wen I did the program gave me an 'unsafe!' tag next to it. should i go ahead with this or is it really unsafe?