OCC has published a review on the Diamond Radeon HD5770 XOC
A quote from the article:
>> Diamond Radeon HD5770 XOC Review
The Diamond HD 5770 XOC graphics card is definitely one product that lives up to its name, by almost maxing out the core and memory with a factory overclock. This resulted in there only being around an additional 5% of overclocking headroom left, which doesn't sound like much, but isn't too shabby on Diamond's part, as most manufacturers only provide mild overclocks on their cards. As such, this card performed better than the other mid-range and entry level products we looked at, including the other HD 5770 card in most benches.
>> Diamond Radeon HD5770 XOC Review