Anyone with experience overclocking laptops? (6820/7820HK)

Does anyone here have any experience with overclocking laptop processors? There are some good deals right now on 6820HK processors, and I'm thinking upgrading my laptop. It's 3 years old, and has a 4710HQ + 980M, and am wondering if I will notice a big difference if jumping to something like a 6820HK + 1070. I play Cities Skylines once in a while, and that is a fairly CPU intensive game, but can also be GPU intensive. But even the 4710HQ and 980M bake in the game (80-90C) and those aren't overclocked. I'm wondering how the 6820/7820HK processor which can overclock actually fair with... well, overclocking. Can laptop power bricks even handle much overclocking?

Just to throw it out there:
1. this is a really bad idea
2. Intel is pushing six-core CPUs out soon, so wait for those if you do

With those out of the way, I don't own a laptop that can overclock its CPU (my gaming laptop predates the K mobile quads by a generation), but understand that you're going to be TDP limited here. If you want to go down this route, you'll need to be very specific about the system you purchase, and probably need to take it apart and ensure that you're getting good mating with cooling elements etc. You'll also need to pay close attention to fan speeds and controls, and you'll have to be willing to deal with more fan noise.

And if I were to make a recommendation: get a desktop gaming PC and a laptop for work. If you need some mobility, build an SFF. Gaming laptops are already exercises in compromise and trying to push CPU clockspeeds just makes everything worse.

Laptops - unless it's a custom gaming one that offers overclocking from the factory as an option which means it'll have a cooling solution in place to handle that - are not really good for overclocking. They are designed to operate at given thermal levels even maxed out and if you're attempting to go beyond that with even minor overclocking you could end up frying the supporting circuitry even if the CPU or GPU is still in-spec as far as the TDP or the Tjmax might be (and 80-90C is still quite a ways off from the Tjmax of the i7-4710Q at 100C - hell, my old 1st gen Core Sandy Bridge i7 regularly goes 95-98C during HandBrake encodes and it's fine).

The issue is that not only the CPU and GPU get hot inside the case so as stated, you're risking damaging the other components indirectly more so than the CPU or GPU themselves directly. Besides, a small boost of 5-10% in either the CPU or GPU speeds isn't going to present you with a very noticeable performance boost considering the risk to the whole laptop with doing it - you'd also be putting a strain on the power supply itself too in some degrees even if, again, the CPU and GPU remain in-spec in terms of performance and power handling.

I'd say if you want to get a quick and simple boost in frame rates for almost any game, lower the graphics options a notch or two depending on how the controls of the game engine work. That can and will give you a nearly instant jump in performance at no cost at all and will even cause the CPU and GPU to work less, use less power, and voila, cooler too.

Not worth it and no they are hard, main problem is cooling, you can not over clock it to anything that will make any difference.

I'm not sure about it being useless. I can push the 7700HQ in my laptop to -0.175v. Its like 0.90v VID effective under p95 blend; about 25w maximum cpu power draw.

If the multiplier was unlocked, I think there's enough thermal headroom for at least 4ghz all core. Stock is 3.4

Honestly, the best thing you can do is undervolt using Throttlestop (Google). It will help prevent your CPU from throttling, allowing higher performance for longer durations.

I play a lot of cities skylines on my desktop

It's one of the few well multithreaded games so waiting for the 6 core coffeelake HQ laptops would be worthwhile

1070m and 1080m have a a lot more power than their equivalent 900 series

I have no issues overclocking my Dell Vostro 3450 GPU...makes a noticeable improvement and makes a lot of stuff more playable at 1336*768 resolution

Depends on the laptop and its cooling solution. Find a laptop with the biggest PSU you can if you're really serious about overclocking. Forget the 6xxx series, the 7820hk runs cooler. Be prepared to repaste and change fan curves. After that you'll have to undervolt it to drop temps further. I could get my 7820hk running at 4.3 around 80c at full load. I didn't try to go higher, because it was pointless. If I remember correctly the Alienware 7820hks are running at 4.4 out of the box.

Apparently the Aorus guys got the 7820hk to run higher than 4.4 - the X7 comes with a 330w power adapter - I don't know the specifics of the overclock, but I'm guessing the fans were maxed out and maybe liquid metal thermal compound.