Overclocking learnings on an i3-540

[ik9000]

So for years I've owned this CPU. Finally got the impetus to see what this overclocking lark is all about. Here are my results so far after a weekend of tinkering. Still more to come, this is just where I've got to (and I haven't followed a guide other than to find out what the sensible stop voltages are so I don't kill the thing). My aim was to get to 4GHz, and it stumped me for a while, but then I got there. Now it's to get as close to 4.5GHz as possible on air without breaking it.



Without doing much to the voltage at all you can hit 3.7-3.8GHz easily. either 3.74GHz with 1700MHz on the RAM (22x170 multiplier CPU, 10x170 on the RAM) or 21x180 CPU and 8x180 RAM. Struggled to get the RAM stable above 170x10 although I didn't really try to boost the VRAM which might have helped, and didn't try too much to relax timings (2 failed attempts). Couldn't get 23xCPU multiplier to work at 1.2V (didn't play with boosting Vcore at this point)



I hit a ceiling here and struggled for a while thinking my RAM wasn't up to it, until I discovered you can select the RAM to run at a lower speed (which appear to be a multiple of the BCLK and equate to be approx 6,8,or 10x in my BIOS settings)

After a Bumping VCPU/Vcore up a bit and giving the VRAM a small nudge 21x200 CPU and 8x200 RAM gives a stable 4.2GHz and has the RAM back at its rated 1600 when using the 8x option. Single thread at 66% of world ranking in passmark, and overall CPU at 39%. Not amazing by modern standards but not bad for a budget processor from 2009!





Tomorrow I'll try upping the bclk to 213 which should get the RAM to 1700 again. If that holds stable with 21x multiplier (4.47GHz) then I'll try upping the multiplier back to 22x (4.69GHz) but from what I've read on line above 4.5GHz is unlikely to be stable on air so I'm not expecting too much. I can also try 22x200 for 4.4GHz and see whether the benchmarks prefer the slightly faster Blck (and RAM) or not.

Then I can try tightening the RAM timings and bumping up VRAM to see whether it could go less latency/higher speed respectively. Probably muck around with that under 4GHz to get a feel for whether it could do more than 1700MHz, I'd hope to get it to 1800MHz, but we'll see...

I appreciate this is years too late to be current news, and anyone with Sandy Bridge will be 4.5GHz just off their multiplier, but this is an i3 on an H55 chipset - are today's cheap-end CPUs this accommodating?

[ik9000]

So after a wasted evening tinkering, I can't seem to get a stable bclk above 201 nor a stable mutliplier at 23x. I got successful boots off 4.3GHz and 4.4GHz, from various combinations but beyond getting a few screen grabs of CPUZ they fairly rapidly crapped out. 4.5GHz would crash out at the log-in screen.

I had Vcore up to 1.3V and moved the Vram to 1.65V (max recommended by Corsair for the 1.5V modules). There's probably some of the other settings I need to take off auto to help this, but I think I would need more than 1.3V on vcore and the searching I did suggested that was a sensible threshold to stop at to not fry the thing.

If anyone has any pointers I'd welcome any tips.