What makes a CPU good for gaming in 2017?
August 12, 2017 1:15 AM   Subscribe

I like to build my own computers, though I don't really know what I'm doing. I thought that processor speed, followed by number of cores, were the determinants of CPU quality, and I have bought the fastest I could afford. But now I find that some slower processors are more highly rated than much faster ones on Tom's Hardware and PC Gamer, and I'm confused. Could you explain CPU quality-- and gaming builds in general -- like I'm five?

If instead you feel like telling me "your CPU doesn't matter as much as your [thingamajig] and here's what you want in a [thingamajig]," don't hold back.
posted by pH Indicating Socks to Computers & Internet (14 answers total) 2 users marked this as a favorite
Your CPU matters, but if by "processor speed" you mean clock rate i.e. GHz, then unfortunately it's not that simple.

We hit the practical limits for raw speed years ago. These days, the performance game is all about making the CPU do as much useful work per cycle as possible. So higher-end processors might have bigger caches, so they spend less time waiting for the relatively slow RAM; more sophisticated ways of juggling lots of simultaneous in-flight instructions; or a more powerful instruction set that allows a single opcode to do more work. So two processors with the same clock rate, but from different generations or different price ranges, can have huge performance differences.

Within a single CPU series, higher speeds generally mean better performance. But when comparing across different models or manufacturers, there isn't really any alternative to just looking at real benchmark results.
posted by teraflop at 1:32 AM on August 12, 2017 [2 favorites]

To put things simply - videogames are comprised of various parts. Some parts can be helped by a faster processor (Civ6 for example is highly single threaded) and some parts are helped by a faster GPU (Doom is not very CPU intensive, but can be highly GPU intensive).

As for CPUs.... its complicated. The main metric is IPC - Instructions per clock - but even that isn't a 1:1 metric. Its complicated.

If you're looking for a simple measure - you need to look at benchmarks that approximate what you'll be doing.

All of that being said, what I do is buy the best MB and RAM I can afford. Then the cheapest CPU and best GPU. I'll upgrade both, but the MB is the biggest PITA to replace, so that is where I spend my money, and GPU second. CPU is dead easy to upgrade, so.... it will wait. GPU has proven to be far more important to the games I play. It is entirely possible that this is not your use case, but still. CPUs are cheap as they age. MBs/GPUs are not.
posted by Pogo_Fuzzybutt at 1:39 AM on August 12, 2017 [2 favorites]

To make things more complicated, some games are CPU bound while others are GPU bound. Minecraft, for example, is CPU bound, meaning that the most amazeballs GPU ever is meaningless for good performance for that game. Lots of RTS/Simulator type games are CPU bound--Cities: Skylines, Civ, Rome: Total War, etc. MMOs also also tend to be CPU bound. Some other games are more graphically intensive, and those tend to be more GPU bound. Crysis 3, various Assassin's Creed games, Borderlands 2.
posted by xyzzy at 2:07 AM on August 12, 2017 [2 favorites]

A good quadcore intel i5 is a very reliable buy for gaming - I think AMD are coming up from behind, but Intel is still the overall champ afaik. But basically processors generally just need to be good enough, while GFX cards you'll see a benefit from whatever power you put into it. I still have an i5 4570 from 2013 and it's basically fine, though probably getting near due for an upgrade.
posted by Sebmojo at 3:15 AM on August 12, 2017

Specifically, my upgrade mantra is the best i5 you can afford, 8 gig memory (doesn't need to be fancy), 256 gig SSD for windows and a couple of games, and something like a GTX 1060 or 1070. That will murder any game in existence for a good long while, at a reasonable price.
posted by Sebmojo at 3:17 AM on August 12, 2017 [2 favorites]

My purchasing method for a CPU is slightly different to other peoples.

For any processor type the price slowly increases and then, at a certain point, shoots into stupid pricing territory. I buy the one just before the price goes nuts.

I have no idea how good this methodology is!
posted by mr_silver at 6:12 AM on August 12, 2017 [5 favorites]

Core and thread count keeps mattering more, too, though, especially if you're ever doing anything that isn't gaming.
Right now-ish the same money gets you an i5 with 4 faster cores or a Ryzen 5 with 6 slightly slower cores. In games they trade blows, depending on whether the game wants a few very fast threads or as many threads as you can give it. In most things that aren't games, the R5 eats the i5 alive because 6 cores/12 threads gets shit done.
posted by ROU_Xenophobe at 9:05 AM on August 12, 2017 [1 favorite]

At the moment, most games don't scale across multiple cores well or at all, so if there's a bottleneck on the CPU, it's with single-threaded CPU performance, and so the current wisdom for gaming is to get a CPU that has really good single-threaded performance as that will get you the most bang for buck when gaming. That's why most sites recommend something like the i5 7600K for gaming, as the extra threads you get with an i7 or i9 don't end up mattering as much, and can often have slightly *worse* single-threaded performance than an i5.

Ryzen is interesting in that they're at least competitive with Intel's single-core performance, but they shine under multi-threaded workloads, which isn't something as useful for games. That said, they pack more cores/threads per dollar than Intel does, which (at the moment) makes them a much better value for multi-threaded workloads like video/content creation. Even for gaming, there's definitely an argument to be made for them in terms of value, even if they don't quite match Intel on single core performance.

All of that said, there are some signs that there may be more of a shift towards better support for multithreading in games as newer graphics APIs (like DirectX12 and Vulcan) add better support for it, so multicore CPUs may start mattering more. Also, if you're the sort of person that tends to have other things running while you game, or you do any game streaming, a CPU with more cores/threads can help your overall system performance there as well.

tl;dr: there isn't really a best processor for all workloads as there are various tradeoffs made depending on their exact configuration, and for gaming in particular you might be spending more money on additional threads/cores that don't measurably improve your in-game performance (at least for now in 2017).
posted by Aleyn at 1:10 PM on August 12, 2017

For either a full new build from scratch, or as a guiding principle for upgrading / repurposing, I'd stick to the following priorities:

1. Spend the most money on a monitor - you'll get much longer use out of a decent one bought today than any other major component, and there are some lovely newish shineys out there like 3440 ultrawide resolution, high refresh rates and GSync / Freesync which (depending on the kind of games you play and your computer use outside of gaming) have a very immediate impact on how "quality" your setup feels in daily use.

Also, knowing the combination of resolution and refresh rate that you want to be able to drive, when combined with a list of games you want to play, kinda helps all the choices further down the list fall into place, both in terms of what you buy and whether you save up for longer to buy something more powerful. E.g. I now have a 3440 monitor, it's beautiful, I love playing all sorts of games on it, but I'm holding off playing Witcher 3 until I can afford a GPU (and maybe CPU) upgrade which will let me run it native with most of the shineys.

2. Next spend on a sizeable, fast SSD - having OS installed on this, plus as many games which have to load large amounts of level data or textures as posisble, will be another big jump in quality feel.

3. Then, for everything which follows, only spend if your current setup can't run several games you really want to play at whatever you feel is an acceptable frame rate / resolution. I assume that all of it will get upgraded eventually... with that in mind I follow these rules of thumb...

GPU ahead of CPU... generally more games are GPU than CPU bound.

CPU cooling and case fans ahead of CPU upgrade... if you're willing to delve into overclocking.

If GPU has been recently(ish) upgraded, and several games aren't where you'd like them to be, upgrade CPU.

When upgrading CPU, if not replacing mobo, buy as high end as you can afford within current socket... and look into cooling for overclocking.

If replacing mobo, do lots of research on current sockets and what seems to be in the pipeline for new CPUs within that family. Spend relatively more on a mobo with better overclocking features rather than the CPU itself, with a mind to next time through the cycle upgrading to the top end (now old) of that socket and overclocking it.

Consider new PSU / case each time mobo is replaced.

When replacing mobo, budget a bit extra for at least 16gb of whatever is currently "fast enough" RAM. Don't waste money on fancy RAM.
posted by protorp at 1:42 PM on August 12, 2017 [1 favorite]

Don't overthink things.

It's just like buying a car - you can try compute the track lap time, or 0-60mph time or fuel economy by number crunching the power output, torque output, peak torque band... what kind of rubber compound the tyre uses, what size tyres are on the car, is the drivetrain FWD / RWD / AWD, what kind of AWD is it....

Or, you could just test it out or find out from someone who has what the real 0-60mph time is and how much fuel it consumes on average on a trip.

There are numerous sites that benchmark multiple different processors under different load conditions, for example Anandtech is a good one, this particular page shows the performance of the new AMD Threadripper and Ryzen vs Intel Broadwell and Kaby Lake while playing Ashes of the Singularity.

Just pick the workload that matters to you, and look up the benchmarks, and make up your mind as to which part meets your price / performance sweet spot.
posted by xdvesper at 6:53 PM on August 12, 2017

i5 7600K for gaming

Useful point to note, the K means you can overclock it which is a good safe way to squeeze a bit more (~10-15%) performance out of it, but does also require an overclocking friendly motherboard.
posted by Sebmojo at 8:01 PM on August 12, 2017

Things are weird right now. There are very few games out there that will be significantly CPU bound on anything newer than a decent Sandy Bridge i5, 4 cores/4 threads at 2012 IPC is still fine for a gaming rig. So much of the physics load is on the GPU these days, you have to be running at stupid low resolution to be CPU-bound to the point you can't get 60fps with an appropriate video card.

With that being the case, though Ryzen is a bit slower per clock per thread than Intel's latest chips, they're just fine for gaming since they easily match Intel's per core performance in 2012 (not that Intel has made huge progress since for most tasks anyway, which is why an old CPU is still perfectly usable for gaming) and can provide serious help for certain workloads that scale better across multiple cores than most games (or for streaming a game while playing or whatever) since you get far more cores per dollar than with Intel.

Most games will make good use of 2-4 threads, but that's about it. Performance gains are fairly limited beyond that. Older ones that don't multithread well don't really matter either since again they are old enough generally that any modernish processor will have the single threaded performance to run it well enough.
posted by wierdo at 11:07 PM on August 12, 2017

i heard that, after cpu, the next thing that affects speed positively is a truly-independent graphics processor (some 'share' something with your normal processor or something, you must closely check the small print as they mislead often in the big print). Games need fast graphics, it's 'rendering' (painting the picture from the software's instructions onto the screen) that takes all the hard effort, so i assume that would help. I also learned it's one of the few things you can't change after the computer's built. I may be talking down to you btw, i can't plug a mouse in hardly, let alone build a computer
posted by maiamaia at 2:27 PM on August 13, 2017 [1 favorite]

Maiamaia, that's referring to low level integrated gfx cards that use system memory - the specialist cards we're talking about wouldn't do that as they all use their own fast RAM (afaik, anyway). And they're relatively easy to change, though you need to make sure you have enough power to run them.
posted by Sebmojo at 8:50 PM on August 13, 2017

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