The Official PC building thread - 4th Edition

Like sammoris said, the i7s are generally faster than AMD's best CPUs and don't compare except in a few situations or under special and fairly impractical circumstances. AMD can fight with the i3s and even the i5s, but the i7s are a little different. Depending on the situation, AMD's CPUs can be able to come close or even pass through overclocking, but the K editions of the i7s and i5s are still untouchable (AMD's upcoming Vishera might be able to change that, but it will likely be too little- too late for this, granted it's not a highly important goal anyway) because they can simply be pushed farther in performance without using too much power and generating too much heat.

If you were truly dedicated, then you could make do with an AMD CPU for almost all situations without really sacrificing performance compared to the non K edition i7s... However, it would be impractical. What you could do is disable one core per module and give it a high overclock to almost 5GHz or thereabouts. This is not unreasonable and it would be able to fight with the non K edition i7s even if they were overclocked through their BLCK and manipulation of the Turbo settings.

However, it would only work for single through quad threaded performance because it would essentially be a quad core CPU using four modules instead of two like the far inferior FX-4100 and FX-4170. For highly threaded performance, you would leave it untouched except for a little overclocking. Depending on the application, you could switch between these two profiles and have the proper performance. There are two downsides to this, one of which is the main cause of this being impractical.

You'd need to keep switching profiles depending on the application. The second downside is that you'd have higher power consumption in both profiles, granted the high difference in cost between the FX-8120 that you'd do this with and even the cheapest LGA 1155 i7 is probably high enough to negate the cost of the higher power consumption until four to six years after purchase. The problem here is that if you're this dedicated, then you'd be more likely to just pay for a K edition i7 and have better performance than the less practical AMD setup.

I like AMD more than Intel, but I don't think that it's worth the impracticality. I'd say go ahead with an i7. However, if this machine is just a gaming machine, then my answer would be totally different. i7s are no better than i5s for gaming performance and AMD can be practical there except in the most highest end gaming computers. Except in the more extreme gaming computers such as more than even a single Radeon 7970's GTX 670's worth of graphics performance, AMD or Intel can become more of a personal preference sort of choice and whether or not the computer is supposed to do other things that one company might have an advantage over the other in.

For example, if quick sync is important, then the Intel K edition i5s or i7s are the obvious choice and AMD isn't even practical at all. However, yet again, the AMD setup would take a little more work to get running and the process of getting it running with proper performance is somewhat more complex. If I really wanted a high end gaming computer with an AMD CPU, then I'd be more than willing to do the extra work. I enjoy messing around with settings and such. However, it can be difficult to recommend such to other people. Once again, using an i5 might be the better choice simply because it's a little easier and there's still the occasional incompatibility with Steam that would make me shy away from recommending FX to any of the many Steam users.

 

Blazorthon,

I have an AMD 1090T Phenom II 6 core on a Gigabyte GA-990XA-UD3 AM3+ motherboard, with 2x4GB 1333 cas 7 memory, 60GB Patriot Pyro SSD, with GTX-550 Ti video. If my choice tomorrow was to upgrade to an FX-8150 and a Z77 Motherboard or go i5/i7, I'll save the $100+ price difference and stay with AMD. The performance difference for me would not be worth the extra money!

Best regards,
Russ

 

Same here!

 

I agree with the vast majority of this. However, I don't consider the FX CPUS really up to par for gaming, because the per-thread performance is so low, and that is what matters in games. Very few titles can make use of more than 2 or 3 threads, and there are plenty of games out there that need more processing power than the FX series CPUs can offer within the confines of those two or three threads, hence the qualifier - if it's games, Intel all the way (I perhaps should have said, i5 will be a better buy than i7 for games exclusively, but if there's a mixture of games and encoding/processing then the i7 is the best compromise).

The debate on value of performance per dollar can and has run on for months, but ultimately, even if it's paying double the cost for a CPU that offers nowhere near double the performance, for many the extra cost really isn't a big deal on what is the most important part of a non-games machine for performance - spending that bit extra will be worth it.

 

Disabling one core per module equates to an up to 20%-30% performance per Hz boost to the remaining core in each module due to the module's resources not being shared between two integer cores while decreasing power consumption significantly, meaning more thermal headroom for overclocking. These two factors combine for the six and eight core FX CPUs being very capable gaming processors in the right hands.

They can then compete with the non K edition i5s and i7s in gaming performance even when those Intel CPUs are overclocked through the BLCK and manipulation of Turbo settings for an up to ~25% overclock. They can't fight with the K edition i5s and i7s in gaming performance, but they can compete with the non K editions very well in gaming performance. The quad core FX CPUs are not so good with this because doing it leaves them with only two active cores and that's just not enough without something such as Hyper-Threading, but we all know that AMD doesn't use Hyper-Threading right now and probably won't any time soon, if ever.

 

This is not necessarily AMD's fault, but nobody buys the non-K versions of the i5s/i7s because the price is so similar. If you're competing against the major CPUs, you're competing against a K-type. I'm well aware the FX CPUs are far cheaper than the i5/i7s but even with a 20-30% improvement, the FX per-core performance is far behind that of even the first generation i5s, let alone Sandy or Ivy Bridge.
Typically speaking a 3.6Ghz FX-8150 is about even to a 3.4Ghz i7 2600K, which leaves the standard Bulldozer 'core' around 47% of the performance of the i7. Even with the 30% upper threshold of the gains from disabling the second module, you're looking at around 60% of the performance per core per mhz. If you're going to disable one module of the CPU you're likely also to be looking at overclocking given how easy it is on modern CPUs - even entry-level overclockers can get the modern i5/i7s to the 4.4Ghz or so mark. Achieving beyond 4.2Ghz on an FX can be difficult (or at least, difficult below the c.300W TDP limitation of air coolers). That really places them further behind.

If you're on a tight budget or if gaming really isn't much of an issue for you then the plus points of Bulldozer are valid, but if adding 100-200USD to the cost of a complete upgrade/new system is palatable for a considerable gain, or you're a mainstream gamer, the FX series CPUs are just wholly inappropriate.

 

Considering that the cheaper non K edition i5s can be as much as $30-40 cheaper than the K editions, competing with the K edition i5s is suddenly not so important. With the disable one core per module and the overclocking, the per core performance of the 8120 or 6100 (any other six or eight core FX will also do, but any other of each is a waste of money because they might be clocked higher by default, but they aren't binned better and don't overclock any better, although you probably already knew this) can easily compete with the non K edition i5s and i7s even if, through the BLCK and Turbo setting, they are given an ~25% overclock. In this situation, the FXes can easily hit 5GHz and possibly even reach past it often.

FX-8120 = $170
http://www.newegg.com/Product/Product.aspx?Item=N82E16819103961

FX-6100 = $140
http://www.newegg.com/Product/Product.aspx?Item=N82E16819103962&Tpk=fx 6100

Cheapest non K edition i5, the i5-2310, = $180
Cheapest K edition i5, the i5-2500K, = $220

The 6100 would be an effective triple core CPU in this experiment, but since quad core CPUs aren't utilized much more than triple core or dual core Hyper-Threaded CPUs in almost all games, that wouldn't be much of a loss. However, the 8120 is still $50 cheaper than the cheapest K edition i5, so it too is most definitely not in the same price range as the i5-2500K because that's 30% cheaper than the i5-2500K. Also, quite a lot of people buy the non-K edition i5s and even among these people are quite a number of overclockers. Even on newegg, the non K edition i5s that are cheaper than the i5-2500K have roughly 600 purchaser reviews altogether. Sure, it's not the over 2100 of the i5-2500K, but it's most certainly not merely no one.

Your math is kinda off about how much the i7-2600K is faster per clock per core than FX. Sure, it's that much faster per core, but not per thread. Hyper-Threading is a substantial boost in highly threaded performance and without it, the i7s are one to five percent faster than a similar i5 at the same clock frequency, if even that much. Not counting Hyper-Threading, at the same frequency, an FX core is about 60-65% of a Sandy Bridge core. With this disable one core per module idea, that is improved even further. Even assuming the minimum, 20% (25% is far more likely in any given situation and 20% is a very worst case scenario), that's brought up to about 75% of a Sandy Bridge core. Including Hyper-Threading, then sure, the FX still falls short. However, that's not important. Any situation where Hyper-Threading is significantly helpful is a situation where AMD is likely to perform well enough to compete with the i7s in highly threaded performance by default with all cores enabled rather than only half of the cores with the same module count and as I've said, although it's a hassle, you could switch between the disabled core count and the standard core count profiles depending on the application. If you find a way to treat the second core per module as something like a Hyper-Threaded thread instead of a real one (although it is a real integer core, unlike Hyper-Threading) and use

Going up to the much more likely 25% brings it up to about 78% of a Sandy Bridge core. The non-K edition i5s that are still more expensive than the FX-8120 can't even really hit past 3.8GHz or and the FX would easily hit 5GHz and likely even a little farther. The math here is fairly easy. The two would perform almost exactly on-par with each other if both were given a proper overclock. At 5GHz, the now modded FX-8120 can easily compete with a Sandy Bridge i5 at under 4GHz in performance per core. An Ivy Bridge i5 would have a notable lead in this example, but the cheapest of those is the $200 i5-3450 and that would be more accurate to what you said about being too similar in price to the K edition i5s, such as the i5-2500K, because the i5-2500K is only 10% more expensive. The FX would still use a lot more power, but i's still much more power efficient than it would be without the mod and might beat the i7-920 in highly overclocked power efficiency. It's not much of a victory and like I said, takes more work than just using Intel, but it is a viable option for people whom want AMD gaming computers, but don't want to compromise performance.

The 8120, with this mod, would use significantly less power than the FX-4100 at the same clock frequency and would have little trouble with hitting 5GHz. Still, it wouldn't be nearly as power efficient as an i5 of the same performance and would need a little more work to set up, but the point was never that it was superior (which it obviously isn't), only that it is a viable alternative if AMD is preferred in a given situation without sacrificing performance. Even the stock cooler for the 8120 could take it to about 5GHz with this mod in use.

Also, I never said anything about disabling modules, only disabling one core per module. Disabling whole modules would be like turning the 8120 into a 6100 or a 4100 with different frequencies. It would not have the performance per Hz per core boost and would have slightly inferior overclocking due to the power consumption not being spread across the chip and instead being more concentrated in a smaller area, although it would be superior to the 4100 and to a lesser extent, to the 6100 due to it having superior binning. Having one core per module and four modules means that your cores are more spread across the chip and this means a lower energy consumption density and that can help make more stable overclocks due to any particular region being less likely to overheat. Beyond that, it means that no one side of the chip has a higher energy density than the other and the energy consumption can spread the heat across the chip more evenly. This can help a little with getting the heat off of the chip and to the IHS.

I'd take a K edition i5 or especially i7 over this, but I won't deny that it is viable, still granted that it's a little more work. If someone already has an AM3+ compatible motherboard and wants to upgrade from a weaker AMD CPU, then this is most certainly a superior alternative to replacing the motherboard and the CPU in order to use Intel to upgrade if you don't mind not quite reaching the K edition performance levels. It's most certainly far cheaper in this way and to an extent that not even the considerable power consumption difference could make the Intel solution cheaper over time except in a very long time.

 

Blazorthon,

For me it's a "No Brainer", I buy an FX-8150 drop it in my socket AM3+ 990XA MB, and smile a whole hell of a lot! Total cost for me? $214.49 delivered, and I can do SLI or Crossfire, if I still want to play some more!

Best Regards,
Russ

 

I certainly wouldn't mind doing some comparisons of my own. I'm sure it would smoke my 965 quad in a great deal of instances...(and I say this fully aware of the single core performance)

Electrical usage won't bother me one day soon. Lets just say I have a scheme planned, that will save me a substantial amount on my electric bill. When it works... I'll post about it

 

Good discussion.

I choose i7 because he wanted "whatever's best" and is like the old saying "jack of all trades, master at none" which means some graphic design, some CAD rendering, some audio/video production/encoding, tester of all Linux versions etc. etc. and so and and so forth.... He's a huge console gamer who makes spare cash hacking XBOX and PS3 but only plays minecraft on PC. he wants the system to be good enough for anything modern as he wants to dig deeper into PC gaming territory.

Once I spec a CPU+mobo, i will probably tell him to save money in the GPU area since most of his usage of this machine will be using 42"HDTV as monitor. Buy a better GPU when you decide to use a monitor better than 1080p. Any faults with this line of thinking?

 

Problem is that with fairly high end graphics, the 8150 can be a severe bottle-neck for CPU limited games.

 

That seems very reasonable to me. I'm not sure if an i7 is overkill or not for him, but the logic that you're using seems sound.

 

Indeed, anything you find yourself needing crossfire for, you'll probably find you need a lot more CPU power than the FX-8150 can provide.

 

Nope, I don't think you'll see the difference unless you are a Benchmark boy.

 

It would depend on the game and the graphics, but the 8150 without the minor (but very helpful) mod that I've mentioned and a very high overclock can be a huge bottle-neck. It could be the difference between over 35FPS and about 60FPS in several CPU limited games at regular settings with some graphics cards. That's most certainly noticeable.

 

Will you see any difference, TRULY, between 35fps over non-interlace 60fps? I don't think so, and that is the true argument here. Also I don't think it is double either!

 

Sandy Bridge has a roughly 50% lead in integer performance per clock and floating point isn't a favorable at all for AMD either, although it's a somewhat better comparison. If FPU performance gets mixed in, then that lead can jump up even higher. There are also other factors to consider. Yes, maybe 35 versus 60 might be a little too much, but it's not nearly double, it's only 70%. Considering both FPU and integer heavy work, that's actually reasonable for some of the more CPU limited gaming workloads. For some, it might be more like 40 versus 60 or so.

I can see the difference between 50FPS and 60FPS. 35FPS looks like crap in comparison. Heck, I even know a few people who complain about motion sickness with very low frame rates such as that when playing high-paced games. Heh, don't get me started on the difference between 60FPS and 90-120FPS on a 120Hz display.

 

I've played with both and I'm not seeing it the way you are, sorry. I've had this discussion with Sam and he thinks experience isn't important but benchmarks are. What a joke as I'll take experience any day over BS.

We will have to disagree I think, no offense Blaze...

 

No offense taken. Agree to disagree.