I have been playing with my 4850 today. After fitting an Accelero S1, I flashed the bios (to remove the CCC overclock limit) and pencil modded the GPU voltage to 1.3v. The S1 fitted with a 120mm fan keeps things nice and cool, and the extra voltage gives a sizeable overclock.
Stock clocks of the 4850 are 625core/993mem
On the stock cooler maximun OC was 675core and 1075mem
With the S1 and stock volts maximun OC was 675core and 1125mem. Clearly the core needed more voltage but bizarly the memory clock inreased by 50MHz without any ramsinks. I guess the 120mm cools them better.
With the S1 and volt mod I get 840core and 1125mem with 100% stability so far. I can run some benches at 875core but others crash at that speed.
See results below.
The biggest surprise for me is that the card does not appear to be memeory bandwidth limited. I thought DDR4 and a measly 256bit bus would limit the benfits of a high core overclock. There is obviously not much real difference bettween DDR4 and DDR5. ATI must just use the available bandwidth very efficiently.
edit: The 3DMark05 scores seem heavily CPU limited. Raising or lowering GPU core and mem speeds makes almost no difference, other than in test 3.
edit2: 3DMark Links Added
3DMark03 Stock 42688 3DMark03 OC 53040
3DMark05 Stock 20826 3DMark05 OC 22770
3DMark06 Stock 12287 3DMark06 OC 14784
Stock clocks of the 4850 are 625core/993mem
On the stock cooler maximun OC was 675core and 1075mem
With the S1 and stock volts maximun OC was 675core and 1125mem. Clearly the core needed more voltage but bizarly the memory clock inreased by 50MHz without any ramsinks. I guess the 120mm cools them better.
With the S1 and volt mod I get 840core and 1125mem with 100% stability so far. I can run some benches at 875core but others crash at that speed.
See results below.
The biggest surprise for me is that the card does not appear to be memeory bandwidth limited. I thought DDR4 and a measly 256bit bus would limit the benfits of a high core overclock. There is obviously not much real difference bettween DDR4 and DDR5. ATI must just use the available bandwidth very efficiently.
edit: The 3DMark05 scores seem heavily CPU limited. Raising or lowering GPU core and mem speeds makes almost no difference, other than in test 3.
edit2: 3DMark Links Added
3DMark03 Stock 42688 3DMark03 OC 53040
3DMark05 Stock 20826 3DMark05 OC 22770
3DMark06 Stock 12287 3DMark06 OC 14784
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