Overclocking the i3 540 on the Gigabyte H55M-UD2H past 4Ghz

These i3’s can really be made to scream…. or so I’d heard.

After doing a little preliminary research on this chip (and the Intel chipsets it runs on), I decided to give it a go. From what I’d gathered, overclocking these things should be pretty simple. Unfortunately, the integrated memory controller gave me huge issues where I’d fail Prime95 even at sub-4.0Ghz settings.

Eventually I got to 4.18Ghz stable. Settings that varied from default were as follows:

  • All power saving stuff turned off (CPU Enhanced Halt, C3/C6/C7 State Support, CPU EIST Function)
  • CPU Clock Ratio : 22 X
  • QPI Clock Ratio : Auto
  • BCLK Frequency : 182
  • Extreme Memory Profile (X.M.P.) : Profile1
  • System Memory Multiplier (SPD) : 8.0
  • CPU Vcore : 1.30 V (later reduced to 1.25 V)
  • QPI/VLL Voltage : 1.29 V (later reduced to 1.21 V)
  • DRAM Voltage : 1.64 V
  • DRAM Termination : 0.78 V
  • Ch-A Data VRef. : 0.78 V
  • Ch-B Data VRef. : 0.78 V
  • Ch-A Address VRef. : 0.78 V
  • Ch-B Address VRef. : 0.78 V

So how did I arrive at those? As I mentioned earlier, Prime95 was failing very quickly regardless of the changes in CPU/QPI/BCLK settings and CPU/QPI voltages. Eventually I got fed up and figured I’d use a high CPU&QPI&DRAM voltage and crank all the rest of the voltages up one notch. It actually worked!

Of course the problem was that my temps were through the roof. They hit 105* almost instantly during Prime95 which is not only worrisome in terms of heat, but also starts throttling the CPU. I backed off the PCH Core and CPU PLL to auto and left all the ram settings. Temps dropped a lot with just those 2 returned to normal. The max temperature I hit with Prime95 in an hour was 102* for a moment.

Still, that temperature’s still high, which is why I dropped the CPU to 1.25 and QPI to 1.21. That shaved off another 11 degrees.

I should note at this point, that these high temps weren’t with the dinky heatsink/cooler that comes with the i3 – I had an i7 stock heatsink that I modified with a dremel to fit (incidently if you mod the i7 (1366 variant) sink to fit the i3 (1156) socket, you’ll lose out on a ram slot because of the size).

Again I’ll note that the computer was pretty stable at this point despite the high temperatures. No crashes, Prime95 didn’t throw any errors for the 2 hours I ran it, and OCCT didn’t throw any errors during it’s run. Memtest86+ also came in clean for a pass.

At this point, I’m just doing a little bit of voltage tweaking to try and drop the temps a little more (and then maybe push for higher than 4.18Ghz).

For those who are trying to overclock the i3 and are running into problems, there are a few suggestions I’d make:

  • Your QPI clock ratio will eventually have to be adjusted (assuming you’re bringing up the BCLK) to keep the QPI Link Speed at a sane level.
  • I had massive issues if I left the Extreme Memory Profile (XMP) at it’s auto setting. If you’re having problems that might be attributed to the memory controller or RAM, either enable an XMP profile (if your RAM supports it), or manually adjust the RAM timings.
  • Don’t go too high on any voltages. The i3/i5’s are prone to sudden death with no warning. They’ll pass your stress tests and die while you’re browsing the web (that’s what I mean by no warning).
  • Your DRAM voltage shouldn’t be any more than +0.5 V over the QPI voltage, or your chip might fry. If you start cranking up the DRAM voltage, check to make sure you’re not exceeding this limit (you may have to bump up the QPI voltage to stay within range).
  • QPI voltage can affect the BCLK you reach, and memory stability. CPU Vcore affects the processor speeds you hit. If you’re not sure which is limiting you (the QPI or the processor), drop the CPU Multiplier and see if you can get the BCLK higher (if it doesn’t go higher, you probably need more QPI)

Finally, just because my settings worked for me, doesn’t mean they’ll work for you. Be careful and gradual when changing settings, and research beforehand as to how high you can go. Overclocking brings risk of damage with it, and if you burn out your CPU, your warranty won’t cover it. Keep that in mind, and overclock at your own risk.

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  1. stop wasting your energy. I also have the i3-540 on the GA-H55m-UD2H (v1.3) and all I did was set the clock at 174 (*23=4.0GHz) and set memory divider to 4 (gives 1392MHz) on 1333 Kingston ValueRAM. NO voltage adjustments whatsoever. Intel graphics work but did not test very long; using ATI card.

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