Overclocking
Disclaimer: Overclocking your CPU means operating your CPU and motherboard outside of their design specifications, it can cause damage to them or kill them, and may void their warranties depending on the manufacturer’s policies!
With that out of the way, we can move on to the overclocking. Basic overclocking on a “SandyBridge” CPU is very simple, you set the three main voltage levels and start turning the multiplier up until things no longer work right. That’s a simplification, but that really is the basic process.
At stock speeds the CPU runs at 3.4ghz, which is 3400mhz. It gets to that speed by multiplying the “baseclock” (bclk) by the CPU multiplier. In the case of this 2600K it takes the 100mhz bclk and multiplies it by 34, resulting in 3400MHz operation.
The more CPU core voltage you give the CPU the higher it can go, I have had this CPU up to over 5400mhz, but that required a lot of voltage and I had to it cool down to ~75 degrees below zero centigrade using dry ice.
For this review I decided to stick to something somewhat safer and more in line with what a normal user would use: I gave the CPU 1.35 volts to the core (vcore), 1.15v on the VCCIO/VTT, and 0.975v on the VCCSA. The ram was given 1.64v throughout, as that is what the XMP profile I used gives it.
Via raising only the multiplier both the Z68X-UD3 and the P67a-UD4 managed to get the cpu up to 4600MHz. The P67a-UD4 would POST at 4700mhz but would crash while loading windows. The Z68X-UD3 however would load windows just fine, but crash if I put a serious load on the CPU.
Having established the limits of the CPU multiplier I started raising the bclk. This has two effects, for starters the CPU speed goes up, and for bonus points the ram speed goes up as well. This is because the ram speed is also based on the bclk via a multiplier. For my 2133MHz ram it takes the bclk and multiplies it by 21.33 to achieve it’s 2133MHz speed.
With the CPU multiplier at 46x I managed to get the bclk up to 102MHz. This might not seem like much over the 100.3 stock speed, but when you consider the 46x multiplier it becomes substantial. This meant the CPU was operating at 4693MHz! This is a 33.7% OC over the normal Turbo speed of 3500MHz. Interestingly it was perfectly happy to run benchmarks at this speed, despite failing completely at 47×100.3. Sandybridge is strange to overclock that way. It would run benchmarks into the 4750MHz range if I adjusted bclk within windows, but that’s a Benching Tactic, and not a normal user type OC. The bclk being set to 102mhz also overclocked to ram to 2176MHz.
Overclocked we’ll be going through the same list of benchmarks and comparing the previous scores to the new overclocked scores. It is worth noting that every CPU OC’s differently, some will go much further on a given voltage level, and others will barely OC at all regardless of how much voltage you give them. Don’t expect to be able to exactly mirror my settings and get the same results.
CPUz Info
Now we’re talking, this will bump the benchmarks substantially! I’m very impressed with how this Z68X-UD3 motherboard overclocks.
PCMark05
33.7% higher CPU speed, 22.7% higher full system benchmark speed. This board’s ability crank the CPU speed up results in everything running faster. You’ve got to love that!
MaxxMem
Memory performance is up a staggering 33%! Talk about a good response to overclocking! This underlines how important Intel’s switch to the L3 cache running at full CPU core speed is. It is my belief that much of Sandy Bridge’s efficiency as a platform stems from that change.
Cinebench 11.5
Cinebench is up 33.2%, a hair lower than the OC percentage, again the system based on this Z68X-UD3 motherboard is responding very well to a fairly simple overclock!
3DMark Vantage
3DMark Vantage I ran twice, once with just the CPU overclocked, and once with both the CPU and the GPU overclocked to really let things fly. First up, stock GPU clocks, 33.6% faster CPU:
Only 3.8% faster here, though the CPU score is up 30%.
Now with CPU OC’d 33.7% and the GPU OC’d from it’s 800/1000 stock clocks to 920/1100mhz:
14.4% faster with the GPU overclocked 15%. This is primarily a GPU bench at this GPU and CPU performance level. The faster the GPU the more CPU power is required to keep it running at full speed, and it looks like even at stock clocks the Intel Core i7 2600K and Gigabyte Z68X-UD3 combo is plenty powerful enough to feed a Sapphire Radeon HD 5830.
Lastly, I spent a bit of time seeing how fast I could convince the ram to run on this motherboard. The end result is a blistering 2225.6MHz at the ram’s stock 7-10-7 timings. That is mighty fast in anybodies book, and very good indeed for a fairly inexpensive motherboard!
Note that CPUz displays the base memory speed, as this is DDR type memory you have to double it to get the official speed. 2x 1112.8MHz is the 2225.6MHz mentioned above.
