Overclocking the GTX 570 was a challenge. After speaking to NVIDIA about the clock speeds to expect from this offering, the expectation was that it should overclock around the same as the GTX 580 since they are the same core. Of course every card produced will fall somewhere on a bell curve. You will have the overachievers on the far side of the curve, the underachievers at the start of the curve and all the rest falling somewhere in between on the "bell". I can't help but think that this card falls close to the underachievers side of the bell with a fully stable 53Mhz, or about 7% increase over the baseline 732MHz. The increase on the memory was just as slim with an increase 1013MHz, or an increase of 633MHz (6%). This makes this card officially the lowest overclocking "Fermi" derivative I have tested.
The Asus factory OC'd model did a bit better ... but not what you are looking for
The ASUS GTX 570 is a factory overclocked card, so I had high hopes for the clock speeds that this one would reach. NVIDIA's reference GTX 570 was able to reach clock speeds of 785MHz. Seeing as the ASUS GTX 570 was clocked just 43MHz below this, I knew it was going to surpass the reference overclock. In the end, we were able to up the core clock to an impressive 933MHz. Unfortunately we weren't able to get as large of an increase out of the memory clocks. We were however, able to up the memory speeds to 1092MHz. Last but not least, the shader clocks. The factory overclock put the ASUS GTX 570's shader clock at 1484MHz. We of course wanted to see a large increase in clock speeds, and that's just what we got. We were able to increase the shader clock speeds to 1866MHz.
Id use OCCT and run the GPU test ..... monitor temps with the vendor's overclocking utility