2900XT Overclocking

[Xion X2]

All I've been reading on this forum since this card was released is how well it overclocks on good cooling. Guys have been posting 950+ core shots on good water setups on stock voltage. Well, now I'm perplexed.. and more than a bit disappointed.

I'm sitting here w/ an OEM Sapphire 512MB XT topping out at 875 on the core. I haven't tried running the memory much higher than 950MHz, but I was really hoping to get a much higher core overclock than this. Temps aren't a problem; I'm loading at 56C on my watercooling w/ a Maze5 at 875 | 925.

I'm using the AMD GPU tool to overclock with since it's all I've seen people use. Whenever I try to go 900MHz on the core my system freezes. I'm using an 850W Quad-rail Silverstone Zeus PSU w/ two 6-pin PCI-e connectors. One connector has 18A all to itself, the other has around 10A. I've also tried switching to another rail with around the same amount of amps on it to no avail.

From watching the results of Kinc and a few others, it's seemed that an 8-pin wasn't necessary to overclock with. But those were on engineering samples, and I'm wondering if retail models are different or if they simply don't overclock as well as the ES.

Thoughts, anyone? I'm really hoping that I'm missing something easy here, but it's beginning to look like I got a dud overclocker.