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Hd 4850 Overclockin

First, I would like to think Sapphire for making a good card with great cooling (beats any other reference and many non-ref cards). Aside from that, I will obviously be using a Sapphire 4850 with the dual-slot cooler.

My first step before I even got a good feel for the non-OC'd card was to start overclocking, as it had great potential. I initially tried using Overdrive but quickly found limitations.

I found a nice tool known as RBE (Radeon BIOS Editor) and made a custom BIOS for myself incorporating a fan mod, the upper OC limits of the 4870, and most of all, more power (1.2 volts). This got me up to 690-core and 1123-memory mostly stable. I wanted more though (4870 core speeds). So I looked for a while, and found the points to do a pencil mod for my card.

After bumping the voltage up to 1.3 volts at full speed, I was able to achieve 720-core and 1123-memory. I ended up dropping these down to 715-core and 1118-memory though for better stability.

All the clocks I listed were stable though a full 3dMark Vantage run and in the end my card will generally not run over 80C and my card is very stable at 715-1118.

The 3dMark Vantage scores are as follows:

The Following clocks were at Stock Voltage
  • Stock: 625-933 = 5286

The Following Clocks were at 1.2 volts (BIOS Mod)
  • 690-1130 = 5933 (unstable for long term)
  • 690-1188 = 6111 (Very Unstable)
  • 690-1103 = 7192 (Very Stable)
  • 690-1123 = 7240 (Somewhat Stable)
The Following Clocks were at 1.3 volts (BIOS Mod + Pencil Mod)[/LIST]
  • 715-1123 = 7431
  • 720-1123 (Stable) = Full Benchmark Not Ran
  • 725-1123 = 7469
  • 725-1128 = Not Stable

If someone would like me to, I would be glad to send them a pre-overclocked BIOS for their card. I may need the original, depending on the model. Though I will not be responsible for what happens to your card, or anything else.


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Overclock.net › Member Blogs › Hd 4850 Overclockin