Listen to your Ivy Bridge–“Undervolt me!!!!”

So in my last blog post I wrote about another SFF build I created based on Intel’s Ivy Bridge as well as the new 600 series NVidia graphics unit EVGA GTX 670 SC+ 4GB.

I also water-cooled both the CPU and the GPU using the Cooler Master Elite 120 Advanced case and it’s been a blast to mess around with, trying different overclocks on both the CPU and GPU to see what it can handle.

While overclocking I found that Ivy Bridge does tend to be more on the hot side when upping the voltage and frequencies and quite honestly I didn’t see much improvement in things like Battlefield 3.  I will say that in testing I gained ~4 fps while playing BF3 in the biggest map to date Operation Firestorm, but the extra heat output from the overclock wasn’t worth the bump in performance.

I tend to look at performance as a whole, not just clocks or fps, just like shopping for a bargain I’m always looking for the middle ground between price and performance – in this scenario it’s heat vs. fps.

So I thought to myself the Core i5 3570k really rocks it at stock frequencies, perhaps I can work on lowering the temps at stock speeds.  After all my reading on forums about Ivy Bridge it was well known the chips came with voltage higher than what’s required, Intel does this mainly because they don’t run it chip they produce through rigorous stress tests for optimal voltage, they run a baseline that’s safe for all their chips.

So as I have the ASRock Z77e mini-itx motherboard I used their tuning software “ASRock eXtreme Tuner” and began undervolting the chip at stock frequencies all while running prime 95 stress test.

Using offset mode I got all the way down to an offset of -0.215 volts, which had the CPU running at just 0.980 volts!

Of course during a test reboot it wouldn’t even post so I had to start over again after a CMOS reset and be more conservative, I ended up with a offset of –0.195V which leaves the processor running at 1.05 volts during full load at 3.8 GHz.

Undervoltage offset

After running Prime 95 for half an hour the hottest core max temp was 67C with an ambient of 27C (remember that this is a 120mm single rad that also includes a GPU to cool).

I’m extremely happy with this outcome considering my Apogee Drive 2 pump is only running at 1300rpms and both of my Corsair SP120 HP fans are running 1200rpms, the system is about as silent as they can be without turning the pump and fans off completely.  Also before the undervoltage was completed and the CPU was running completely stock I was seeing temps as high as 77C during Prime 95 stress testing which still isn’t bad but it’s not great either.

With temps this low for the CPU I was able to overclock the GPU to a base clock of 1250MHz up from 1130MHz which really improved my frames in BF3 by almost 10fps during Operation Firestorm.  The increase in clock and voltage on the GPU increased it’s output temperature by 2C.

So after all was said and done I got 10 more fps for no additional heat output by undervolting my CPU and overclocking and overvolting my GPU.

Results of undervolting Ivy Bridge Core i5 3570k

I will be running heaven benchmarks with the new clocks soon so that I can post results of clock improvement with the GPU.


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