Lack of L3 cache impact on gameplay?

Hi guys,

I know this is not strictly related to GPUs, but it is related to gaming. Referring to my sig, I have a new laptop on its way shipping to me, with an AMD Phenom-II N930 CPU. One thing that's bugging me is it doesn't have a level III cache.

I actually RMA returned another Acer laptop (also described in sig lol) that had an i5-460M Intel CPU. It has only 2 cores instead of the 4-core AMD mentioned above, and smaller L1/L2 caches, but it does have a 3Mb L3 cache.

My question is, would there be a significant framerate drop in gaming due to the absence of L3 cache on the AMD CPU? Also, relative to the i5-460M, would the AMD processor perform noticeably better, or worse, in demanding games, due to the larger L1/L2 but smaller L3 cache?

And backing off 1 step, would these differences in CPU performance be trivial or major if the same GPU is present (e.g. AMD N930 + ATI HD5650, vs Intel i5 + ATI HD5650) for game framerates?


Thanks!

 

The L3 Cache is the last thing you should be worried about. The CPUs are complete systems, not individual components of cores, caches, etc. The AMD and Intel architectures are completely different, and each is designed differently. The Intel chips are way better, but it's not solely because of the amount/type of cache. Besides, the GPU will be the limiting factor in the vast majority of games.

 

Look at these two pages and compare the performance of the Athlon II with the equivalent Phenom II. The only difference between the desktop Athlon II and Phenom II is that there is no L3 cache on the Athlon II. There is not a whole lot of difference.
Charts, benchmarks Desktop CPU Charts 2010, 3DMark Vantage High
Charts, benchmarks Desktop CPU Charts 2010, Gaming: Left 4 Dead 2

 

Great, so for the AMD Phenom-II N930 + ATI Radeon HD5650 combo in laptop, the CPU won't by any means bottleneck the performance? That's quite the relief.

 

Long time ago I did a cache test on 486DX-100 with HMM3 There was an option in bios to disable cache though I don't remember which one was it. With cache it took 1-2 seconds to load a savegame. Without the cache it took like 2 minutes to load the savegame, don't remember how long it took windows to load

Anyway uncached memory access is about 50ns, and suppose some cpu is 1GHz then that cpu might not be doing anything instead of executing 50 instructions if it was cached in L1 cache.

 

Effect of L3 cache on gaming above 800x600 = Effect of shoelaces on marathon times.

 

Wait is that significant? O.O I'm not sure I understand that analogy completely. I mean, the right comfort in shoelaces is really important in marathons right?

 

^^Yea, i think that was a bad analogy. Imagine trying to run a marathon without shoelaces? I don't think the effect is comparable to having a processor without l3 cache.

 

A thread I just came upon on google-search of people discussing performance issues in Starcraft II, seems to have the consensus that only CPU-intensive games (RTS games aka SCII) will be noticeably affected by the presence of L3 cache, and that FPSs/RPGs mostly won't - even if they do it'd be only 1~2% decrease maybe. Is this claim valid?

 

That's about right.

 

'Kay, good. I'm not an RTS person so this is good news.

 

Just look at the benchmarks I linked to. It conclusively shows almost no difference for the current AMD architecture.

 

Well, I got the laptop yesterday.

Its performance are much lower than what I anticipated. I'm guessing a big part of that is because of the CPU nerf... I'm getting much lower framerates in several games than my previous i5-460M + NV GT420M combo laptop, either I'm having some sort of driver problem that is crippling the 5650 performance, or it's getting bottlenecked to hell by the N930 processor.

 

It should perform well, make sure you have the most recent drivers installed, and if you're going to OC the CPU and GPU, use a cooler with it, just to be on the safe side. Oh and you won't notice the lack of L3 cache in games, so don't worry about that. Worrying about it will only ruin your enjoyment with your new toy.

 

Hi,


Here's a few facts about my new laptop:


1) it has ZERO heat issues. I can say it does wayyyyy better than most intel+discrete GPU laptops. the N930 CPU NEVER gets past 67 C, and the 5650 even when overclocked to 725/1000 never goes past 73 C.

2) I've tried all kinds of drivers for the 5650, 10.4, 10.5, 10.10, 10.10e, 10.11, they have zero effect on the framerates in several games I've benchmarked with.


I'm out of ideas as to how I can extract ATI 5650's performance. I know some who benchmarked with NFS:Hot Pursuit with their i5/5650 setups and all of them got consistent 50+ fps, and I'm only getting 25~30 fps with the very overclocked 5650, I'm guessing the CPU has to be the culprit.


Could you share some more ideas as to what I can do? :/ Thanks

 

I don't think you have a CPU issue, but the lower clock speed of the CPU doesn't really help a whole lot compared to the i5 which has a higher clock speed and is generally faster clock for clock. It certainly isn't from a lack of L3 cache... I guess you could try OC'ing the CPU and see if that yields any results. Other than that, I don't really have any suggestions other than OC the CPU and try different drivers and driver settings.

 

That's exactly what I've been trying to do today, to no avail (as I have very limited knowledge in this field). How can I go about overclocking this AMD CPU? I've searched all over google and back and found nothing that remotely gave me hope of success.

E.g. AMD's Overdrive - nope doesn't allow me to adjust anything.
SetFSB - doesn't recognize my chipset, and keeps asking me to pay.
SysTool - outdated
ClockGen - outdated

Please, any idea as to how I can go about this is very much appreciated.

 

btw L3 cache is the slowest...very low

 

Perhaps I should make a specific thread consulting NBR about how I might go about boosting the N930 via overclocking...should I make it in hardware subforum, or in this (gaming/graphics cards) subforum? Which one might yield better success?

 

I'm not sure, never owned an AMD mobile CPU before. Check the Acer forums here at NBR and look for posts concerning OC your specific chip.

 

Lower your resolution to like 800x600 or something and turn a lot of the eye candy off. If performance significantly improves, it's a GPU issue making your game slow. If it stays about the same, then your CPU is to blame.

 

Edit:

Never mind, it DOES do that.

I just lowered all the resolution / effects / textures to minimum in Need for Speed, and the framerate didn't change (still stuck 25~30 fps).

 

How many cores are being utilized when you play?

 

AFAIK it uses most of core 1, and ~30% of cores 2-4, if I quickly alt-tab to task manager from ingame.

 

Estimate what the usage was while you were playing from the graphs.

 

Oh it'd be about 50%.

i5/i7 users also with ATI 5650 seem to do much better (get 50~60 fps with same settings, incontrast with the 20~30 fps I'm getting) with this game. Do you think it's an AMD optimization issue rather than a CPU bottleneck issue?

 

Ahh the L3 cache debating. lol, will it never end. Its like figuring out one more time what the Front side buss actually is on a processor. Iv been in a heated thought about which processor gives the best gaming performance. The i7-640/620m or the i5-580/560m processors. The i7 has 1 more megabyte of L3 smart intel cache but other wise they are identical.

 

We kinda ignored the original topic (because it has such a trivial impact) and the problem right now is the possible CPU bottlenecking in games, with my sig. laptop...

Yeah what's your opinion? Does "partial" CPU bottlenecking occur? Meaning two identical GPUs (in this case ATI 5650), would AMD N930 2.0x4 have drastically lower framerate vs Intel i5-520M or 460M? Because at least for 1 game (Need for Speed - Hot Pursuit) that is true.

 

The CPU could be bottlenecking the game, but it has nothing to do with L3 cache, which is trivial. Based on benchmarks, the average improvement in performance would be in the 5% territory. Some applications might benefit none, some slightly more. Obviously anything GPU bottlenecked gets no benefit.

If the CPU is the bottleneck it is because you basically have a 2.0 ghz athlon ii x4 (in desktop terms), and perhaps this game isn't coded to take advantage of 4 cores. Let's say it's optimized for 1 core. Now you might be in trouble because you basically have a single core 2.0 ghz athlon ii to work with... 2 cores might not be much better. Quad core optimized games will fare quite a bit better for you.

 

Can you get your hands on a copy of GTA IV, it works very well on quad cores.

 

With regards to overclocking the N930, I don't think it's possible. There were a couple HP dv6z owners several months ago who were trying to find a way to OC, but I haven't heard from them in a while. The only mention of being able to OC the N930 came from a Newegg review on the dv6-3050us and did not specify how.

 

From what I've seen in terms of CPU core usages in task manager while in this game, core 1 is getting 80~90% usage, core2, 3, and 4 are getting 40~50% usage. So I'm not too sure as to if it's bottlenecking...

Even if it isn't, how can one explain why peeps with i5 processors and the same GPU get about 80~100% times better framerate in the same game same setting?

Yeah I see you have more or less the exact same specs as mine albeit different brand. What is your mobo / chipset? Mine is JV51_DN / ID9601.

 

Hey Prydeless, sent you a message (about that review guy).

 

umm... I'd put it more like, it doesn't DITA on quad cores like it does with duals.


L3 cache is used mostly in inter-core transfers which occur in highly threaded workloads e.g. video editing/encoding etc. and the benchmarks that Trottel linked to on the previous page show how insignificant it's impact is in the Phenom II/Athlon II architecture.

If anything, theory says the lack of millions of L3 cache transistors putting out heat & sucking battery could result in a better overclock headroom or better battery life (than an identical CPU with L3)

The quad core AMD mobile chips are great performance for their price and TDP of ~25W but are bottlenecked by terrible single thread performance. 1.6GHz of K8 CPU is from 5 years ago!! They would be so much more competitive with a TurboCore/Turboboost technology to remedy this!!

Thus they are a terrible choice for gaming, especially the P920 1.6Ghz quad where very very few games (or commonly used programs for that matter) are very balanced multithread, most still are centred around a linear "main" thread with other cores doing minor things like sound or AI or physics or graphics pre-render stuff. For the games you're playing, 1.6GHz obviously isn't enough to run the main thread fast enough.

It's the same issue the old Q9000 (Core 2 Quad, 4x2.0GHz) had which meant it was really bad in some situations. But that could be overclocked easily to 2.5GHz+ which remedied a lot of that.

The i3/i5 are much better chips because they offer more rounded performance (plus onboard gfx for extending battery)

 

Hi,

That's precisely what we're trying to find out now, if OCing the N930 is possible. The only basis is on a purchase comment of an HP dv6z-3050us made by this guy on Newegg, who claimed to overclock the N930 from 2.0GHz to 2.5GHz without a problem or stability issues, so we're trying to track him down and contact him.

 

I think you missed the whole part about the chip just not being very good, maybe you should return it and get a dreaded i5 laptop.

 

15% restocking fee + paying for shipping back costs, then purchasing a laptop of similar price, with inferior graphics and worse cooling, paying for shipping again, to get a faster i5 processor. I think I'll try as many other options as possible before giving up...

 

Oh sorry,I thought it was from a brick and motar and you could just do a swap. I also thought the graphics were the same.
Funny about how the i5 get's hot I wonder if that model or if its i5's in general?

My i7 and my i3 are nice and cool. Cool enough I use them on my lap with no protection.

 

Same there's no problems with heat here with my i5-520m.

 

3DMark06 score - 8829, that is a fine and dandy score.

For compairson you have to use games that actually utilize the processor. Online mmorpgs(massive multiplayer online role playing games) do this. Do some benchmarks on a free trial of aion/wow or a few free to play ones like lord of the rings online or dungeons and dragons online and compare it with someone with an i5. That will give you a good idea of the difference between the two since mmorpgs rely on netcoding which the processor handles.

 

Well, about the heating/cooling, back when I had the i5/GT420M, the CPU drags the GPU temperature up in games usually (CPU gets to 80+ C, GPU slowly rises, approaches high 70s degrees).

With this laptop the GPU drags the CPU temperature behind. The worst case torture test I had IntelBurn 4-core CPU burning running, plus Furmark GPU burning on. The CPU got to ~70 C and paused, then the GPU started going past 70, and dragged the CPU temperature along until the fans cranked to 100% then CPU maintained about 77 C.

Usually in games I've tested so far, CPU never goes past 67 C. I might test a few CPU-intensive games soon (albeit to likely disappointing results, as the CPU seems to be anemic).