ATI 4850/4870 voltmod thread

[dejanh]

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However, getting the core speed up to max on the HD4870 is a different story. The GDDR5 memory allows this card to scale properly with core speed up to at least 1000MHz (I'd think).

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This is only in theory. In practice there is no way that you will come even close to 1GHz core. 900MHz stable would be very lucky. Granted, one thing is true, the added mem bandwidth does kind of push one to try to push the core as high as possible.

I was just re-reading something and I noticed this...

Hi, at last I've voltmoded my 4870. Thirst of all GPU OC potential strictly depends on Memory clock. Here are some interesting results I've got:
1.283v (default), possible variants:
(GPU-MEM 3DMark Vantage GPU Score)
875-1200 9976

1.300v, possible variants:
880-1200 10005

1.305v, possible variants:
890-1150 10099
880-1200 10007

1.325v, possible variants:
895-1000 9839
890-1050 9983
885-1100 10015
875-1200 9976

1.350v, possible variants:
910-900 9827
905-1000 9967
895-1050 10004
885-1100 10020
880-1150 9998
870-1200 9914

What does it looks like? Right, it's no other then over current protection and 90% that it's located in BIOS (by the way you can check current in gpu-z 0.2.7). So here's Power Play II AMD has been talking about. Well AMD did a good job on failing our OC.
I hope in future versions of RBE we could heal this anti OC protection. Until it's done, no WR on this adapter would be possible. :/
By the way, it was certainly not because of the over hitting (using 1.35V):

You are saying you are not failing due to over heating at 1.35V, but you are running your GPU at 1.263V which is the default voltage (not 1.283V). Try actually running FurMark with 1.35V and high clocks. Otherwise, good observations, there is a definite link between maximum core and maximum memory