Ever wonder what the real difference was between a B3 and a G0 stepping CPU
I spent the last two or three months struggling with a hot and not very speedy B3 Q6600 CPU. I was eventually able to get to 3200 MHz with it, but it took 1.4 volts in BIOS and an hr of lapping IHS to 2000 grit finish to do so. My Prime95 temps at this speed were between 68 and 72 C. At one point, I thought my Patriot Pc-8500 memory sticks with Micron D9 GKX IC's were the problem, so I spent $400+ to get high end Corsair memory with Micron D9 GMH IC's (P35 chipset based motherboards seem to like the GMH Ic's better).
Late last week, I replaced it with a new Q6600 G0 stepping processor. I had planned on getting a new E8500 processor, but it was on back order. This gave me an opportunity to do a comparison between my old B3 processor and the new G0 stepping in the same system, so I set my new CPU to 3200 MHz and worked with it to obtain its minimum Prime95 stable settings.
Here is what I found: My old CPU needed 1.400 vCore to get to 3200 MHz, while my new one needed only 1.2175 volts. My old CPU had load temps of 72, 70, 70, 72 C, while my new CPU had load temps of 43, 39,39,43 C. Note that the old CPU's IHS had to be lapped to try to equalize core temps, so its mating surface with the lapped Thermalright Ultra 120 Extreme HSF was definitely an advantage for heat transfer.
My new G0 stepping CPU has a 8hr Prime95 stable OC of 3752 with 1.3750 vCore in BIOS, but I have my everyday setting at 3600 MHz (9 x 400 MHz FSB) with a vCore of 1.2875 in BIOS (1.296 as shown in CPU-Z). Under Prime95 with these everyday settings, my load temps never exceed 56 C and are usually between 51 and 54 C.
In the end, the difference between a B3 and a G0 processor for me was this: -.1825v (for G0 at max OC speed of B3 compared to B3), -.0250v (for G0 at max 8hr Prime 95 stable OC compared to B3 at its maximum 8hr Prime 95 stable OC), -29-31 C (for G0 temperatures at max OC speed point of B3 compared to B3), and +552 MHz (the current difference between the 8 hr Prime95 stable OC points of my G0 and B3 CPU's).