I remember a lot of people lapping Q6600 G0 for higher overclocks. I have 200 grit sandpaper - if I lap my CPU, will I get lower temps?
if done correctly, on both contacts (cpu & heatsink) with some good thermal paste you might see a drop of a couple of degrees if lucky. i have never seen a significant drop worth the voiding of a CPU warranty.. also, which CPU are you intending to lap? Edit: just saw your running an i930. if its under warranty i wouldnt.
A properly lapped cpu will always perform better than a non lapped one, be warned though, it voids your warranty.
my i920 is lapped because the hs was pretty much warpped and would never make decent contact great now its flat so yes it can be very much worth doing
I've actually got a piece of crap P4 CPU lying around that I could lap for practice. Will my 200 grit sandpaper do the job?
I would start off with about 400 grit, then move on to 600/800 grit, then 1000, then 1500 and finally 2000. It might seem like a lot of work, but if you are going to do it do it right. Its a £230 cpu you are using so make sure you are confident before you start. I know you said you have an old P4 to practice on, but I would do it to a couple before I attempted an i7. I have a couple of P4's I can send you if you need more.
Well what I really want to know is whether I will genuinely see a temp reduction, a meaningful one. I don't hear about lapping being done that often anymore which made me wonder that it isn't as effective as it used to be?
I lapped my Noctua NH-U12P and my E8400 the Noctua is strapped to, and there was a temperature drop of about 3*C on both the cores. With a quad core processor running, the main thing it will do is even out the core temperatures... With my i7 920, I've got a 5*C temperature difference between cores 3 and 4. I'm half tempted to lap the processor, but I won't do it without lapping the cooler, and the Corsair H50 isn't known for having a lot of extra copper to take off. Whatever your lowest core temperature is now, take ~3*C off of that and make it even across all of the cores, and that's where you SHOULD be at. As for lapping itself, use a glass surface (perfectly flat), start with ~400 (I started with 320) grit paper, work up to 2000 grit. Here's my log about it HERE. If you read the thread, you'll notice I had a couple problems gauging temps. Overall temp drop ended up being about 4*C after the thermal paste cured again. Same setup has been running at 4GHz happily for over a year now.
I think in particular is was users of the Q6600 and TRUE that lapped, because the TRUE is often warped because of the way the baseplate is bolted onto the heatsinks (unlike, say, the Core Contact Freezer).
In this case lapping probably won't help. The problem is how the temperature is calculated, not the imperfections of the heatsink's surface.
I lapped my old Q6600 and I saw a 3-5 temp decrease. plus all the cores would idle and load the exact same numbers. I would never ever lap my current CPU now tho, the temp difference is just not worth it.
No, its not worth it. Unless the few degrees temp is essential (i.e extreme overclockers) then don't bother. If you get it wrong then you'll screw a perfectly decent chip. The temp decrease won't make a diff to 99% of people.
I agree, i lapped my Q6600 because i could see a visible defect in the service that i was appalled by it. And when doing a contact testing i found air pockets so it got the lapping treatment. I suspect it would have been fine with the intel stock cooler and its 1mm thick TIM pre applied, but not in my case.
I had to lap both my CPU and cooler as they were way out on flatness. It made a -10C difference simply because it was that bad beforehand. Luckily for me, my PhD is material based so I have access to lovely polishing equipment - both contact surfaces were done to mirror finish! @Ph4Zed: 200 grit is all right as a starting grade but be very careful - perhaps the equivalent of five passes over a 30cm length. Move 'down to ~400 grit for a few more, then ~600, then ~1000. It's up to you how much further you want to go (I have 3000 grit paper, then I'm onto diamond polishing pastes).
i bought a lapping kit and eventually never bothered, not sure where it is now or you could have had it. to me not worth the danger to components but if you're made of sterner stuff......
I wouldn't bother. The temperature decrease is likely to be no more than 5C or so, and you will not get higher overclocks. Most chips, particularly the i7s, hate higher voltages more than higher temperatures. If you're getting extreme temps, it's a badly mounted heatsink (which I doubt yours is), lapping isn't going to do anything for you there. What kinda temps are you getting atm? And really, lapping is mostly useful for very uneven surfaces; what Xlog said is very true.
I'm not having a temperature problem really - my 930 is at 3.9GHz, load temps are around 74C on core 0. This is at 1.35V. I think I've probably just got a bad chip as I was hoping for 4GHz on air.
