Right, so it's been a while since I've done a writeup on anything tech related but I've recently seen a trend I think is kind of...stupid. Basically, I've seen quite a few people buy ultrabooks with ULV 15 watt processors and pairing them with 1080ti's or even Titans.
So I'd like to write a bit about price-to-performance ratio and particularly bottlenecking to help those people and yourself make the best decision when buying an EGPU or maybe any processor GPU pairing.
A bottleneck is when a PC is performing a very demanding application and it appears that some aspect of the application can (or should) be performing better. In games, a telltale sign of a bottleneck is that the video card achieves much lower benchmark scores and performance than what most people with the same setup experience. As the performance of the CPU and the video card are largely responsible for how well the game runs, the blame is put on the CPU for causing the performance bottleneck, hence "CPU bottleneck."
Fortunately, there's one easy test to figure out whether you'll have a CPU bottleneck: Monitor the CPU and GPU loads while playing a game. If the CPU load is very high (about 70 percent or more) and significantly higher than the video card's load, then the CPU is causing a bottleneck.
Now let's talk about mobile processors a bit:
Like most compute tech, processors come in essentially two classes – mobile and desktop. Mobile processors, whether they be for laptops, smartphones, or IOT devices, are generally designed for efficiency first and performance second. Desktop processors being less limited by thermals and not at all by potential battery life, are by far the performance champs and will on average have more cache, higher stock and Turbo speeds, and higher TDP (Thermal Design Power).
Mobile processors do NOT come in the same flavor as desktop processors!
Even though both desktop and mobile processors can share the same i7 (and i5 or i3 for that matter) name, that doesn’t mean they’re equal for the reasons I describe above. For example, a desktop Intel Core i7-6700 runs 4 cores at 3.4/4.0 GHz with 8MB cache for a Passmark score of 9,973. Its mobile counterpart, the Intel Core i7-6700HQ, comes in at 2.6/3.5GHz with 6MB of cache for a Passmark score of 8,001, or almost 20% less. And this is just for quad core HQ processors, let's get a bit into the suffixes you need to notice with your processor.
Mobile Processors
U – meaning “ultra-low power,” these processors are typically found in Ultrabooks and similar style laptops where battery life trumps performance. TDP is usually around 15W but speed suffers. These are typically used in ultrabooks(there's also an M series which is even lower, for the love of god don't even try this with them this is the minimum you want to try EGPU with), the razer blade stealth, surface, even some tablets.
HQ – designated for “High performance graphics, quad core,” HQ processors are found in many gaming laptops. TDP is around 45W but performance is much better.
HK – meaning “High performance graphics, Unlocked,” these processors are similar to the HQ class but can also be overclocked like many desktop processors.
Now, what I've seen a LOT of is people thinking they can get the best of both worlds. That they can grab a U series processor, and strap it onto a 1080Ti and get that level of performance. That's a bit like if I bought the tires from a Bugatti, and put them on a Ford Focus. We still have the drivetrain, low end gears, of the focus, that powerful engine can’t get up INTO its power range at the higher RPMs it needs to run in to propel that car so quickly! It will be faster but not as fast as the bugatti and you won't get the performance you paid for out of that engine.
If you get an HQ or HK yeah it's like stepping up those parts from regular street car to maybe a mustang, but price to performance maybe you'd be better off picking a less expensive engine that provides the same performance.
Maybe you should have just bought a damn mustang in the first place and then a commuter car for the price of the Bugatti engine.
Consider the fact that Razer's core, the most compatible eGPU solution right now costs $500. Without a GPU. The 1080 is around $500, the $1080ti is around $700.
That gives us a $1000-1300 budget to build a sensible desktop PC.
Now I went a bit over budget with this build at $1400 but you're also getting six cores, just as a comparison I'm going to show you some 3dmark scores.
These are the absolute lowest 3d mark scores with that desktop processor, the lowest people have hit without failing
and here are the BEST scores with U series processors.
With a U series and 1080 TI your best performance will be far lower than someone's worst. HQ and HK processors land in a happy medium. More on that later...
If you truly visualize yourself, mostly gaming around one place/area I'm going to give you the most sensible advice I can give you, take the MINIMUM $600 you will invest in EGPU schenanigans and build a decent midrange desktop. Big, small, whatever you like, it will be a more worthwhile investment than this endeavor at this time. Except for the Aorus gaming box, these devices are not very portable and take up the same footprint as a itx PC horizontally, and if you have the vertical space you could have a mid tower.
Or even just get a gaming laptop that performs how you'd like. Maybe even get two, a chrome book, and a get away from me peasant box. With the 10 series mobile GPUs you aren't making the same kinds of comprimises we used to have to make in the mobile space. Spend the extra money, or deal with the slightly extra bulk and it will likely perform the same or better than EGPU because there are other issues to get into regarding this bottlenecking.
The majority of devices(besides alienware) are using Thunderbolt connections. Which introduce a further bottleneck besides the processor, as well as more processing your PC has to deal with. Alienware offers the graphics amplifier(which is what I use) that does eliminate that by using a PCI connection. This is proprietary to Alienware. The device is the cheapest at $200, but their laptops aren't. The cheapest is the alienware 13(which is also what I use) at $1100. For the price of the graphics amp you could simply upgrade to the 1060.
Frankly Alienware had the most sensible option LAST year when their 13 had a ULV processor(as well as the 10 hours of battery life that comes with them, less heat, and a less bulky chassis) and desktop GPUs and mobile had a larger gap. Now one might as well either buy the laptop with the GPU they want or build a desktop that will be user upgradable. Nvidia's Max Q design is even making it possible to get ultrabook form factors out of gaming PC's.
Writing this far it almost sounds like I'm trashing the entire concept of EPGU and EGPU gaming. I'm really not, I'm actually very fond of the concept and hope it goes further! But I'd like to set expectations realistically. These devices are awesome as long as you do! But if you take anything away from this please understand:
you are not going to get 4k 60 fps ultra settings gaming on an ultrabook processor. Even the current upgraded consoles like the xbox one X and PS4 pro are suffering from a similar CPU bottleneck despite their upgraded graphics hardware.
Here's the benchmarks again:
ultrabook:
http://www.3dmark.com/3dm/14697095
Desktop:
http://www.3dmark.com/fs/9673836
without getting into game loops and all of that (and I've written a couple!) jazz any processor that can run all the simulations modern games do physics, AI ect is just going to need more horsepower than 15 watts to keep a high end GPU fed. Maybe if the game is older, or SUPER graphics dependent...
Remember when I mentioned "Price-to-performance" ratio at the beginning? This is where we are going to get into that. Both the GTX 1060, and RX 480/580 are the perfect price-to-performance ratio graphics cards for ANY U series processor. They are the peak performance for those processors I'd say. They will run any game at 1080p ultra settings, some at 2560x1400, MAYBE 4k 30 fps, or with some settings turned down. But once you go past that into the 1070, 1080, 1080 ti(unless you find an amazing deal on one then why not) you are not going to see a ton of difference and in fact with some extreme cards or overclocking can perform WORSE. Here's an example of my 295x2(recently sold...thanks miners for the 1080ti) underperforming a 970
but yeah, 970/560/480/580 are pretty much the limits of what that CPU is capable of. You still have an ultrabook that can outperform all of the consoles and at least hang with xbox one scorpio. If you have a 1050, or 965, you have a ps4 pro that can attatch and become a "pro" console.
Those of you with HQ/HK processors, ya'll got a little more headroom, 1070, 1080, but you have the option to have those cards in the laptop as well where they will perform better due to not having to deal with thunderbolt. That's up to you though. and of course you have the option to upgrade in the future using EGPU which is where it will be most worthwhile. I think I said everything I wanted and needed to say here so I hope you make an informed purchase!
A desktop is going to be your BEST option though if you want a high end card and high end performance!
down from there, an HQ, HK CPU and everything that comes with it including heat, noise, heft, price ect. and finally your u series processor which like I said you don't want to pair with much more than a $200-$250 gpu as of 2017.
here is the aorus gaming box for $600
Here is the Akito node which I forgot to mention, same thunderbolt connection though
I'm not posting the 480 or 580 right now because prices are stupid(thanks miners) if you see it for $250ish though grab it, or whatever card is at that price when you read this in the future..
With coffee lake coming soon we will see the first quad core ulv processors. Stay tuned for when I check them out and write an update!