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AMD releases a new flagship CPU for consumer market with 128M of L3 Cache

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Re: AMD releases a new flagship CPU for consumer market with 128M of L3 Cache

#101

Earlier quoted context omitted.

Or buy an X3D that's homogeneous, like the 5800X3D or upcoming 7800X3D. I have no idea why AMD made the 7950X3D be this weird 50/50 split. Why not make both CCDs have 3D V-cache and make it the true halo part it should be? Then cut costs with the 7900X3D?

Because the added 3D V-cache increases heat. That's also why the X3D variants have lower clocks than the non-X3D versions. Two CCDs with V-cache is apparently too hot.

Previously that wasn't the issue, the issue (according to AMD) was that there was a huge interchip communication bottleneck with the extra L3 on both chips.

If thats fixed, then AMD is just being cheap :P

Re: AMD releases a new flagship CPU for consumer market with 128M of L3 Cache

#102

AnandTech sees some intriguing regressions on certain benchmarks, https://www.anandtech.com/show/18747/the-amd-ryzen-9-7950x3d... ( "CPU Benchmark Performance: Simulation" ) Worst is Factorio, which is down -47% against the 5800X3D (a previous-generation CPU that also uses stacked L3 cache), on the benchmark "10K trains". Wonder what's going on there? - "We would have expected higher performance in our Factorio bench…

[flagged]

Factorio (unfortunately) isn't a very typical benchmark.

The "run AAAs at low graphics at 1080p" trend among review sites is kinda stupid though.

Re: AMD releases a new flagship CPU for consumer market with 128M of L3 Cache

#103
post #13

"AMD Ryzen 9 7950X3D Linux Performance" https://www.phoronix.com/review/amd-ryzen9-7950x3d-linux "AMD Ryzen 9 7950X3D Desktop CPU Review Roundup" https://videocardz.com/150677/amd-ryzen-9-7950x3d-desktop-cp...

the Linux test leaves me quiet confused how to pick my next linux gaming cpu. On the one hand side Gamers Nexus is making a point [0] (there are on/off performance charts later in the video) why it is super important to install the latest windows drivers + special windows gaming software to make use of the heterogeneous architecture. On the other hand side the linux tests are much better then I would expected since i…

TBH if you are CPU bottlenecked in your linux games (hence you need a new CPU), you are probably playing simulation games, and these tests are kinda useless anyway.

Re: AMD releases a new flagship CPU for consumer market with 128M of L3 Cache

#104

Earlier quoted context omitted.

If it's a problem for Factorio it's also a problem for others, so definitely something to fix on the AMD side.

Its more of a fundamental scheduling issue. The unlike big/little cores OS has no idea what apps "prefer" cache or frequency.

An OS can easily run an app on each for a few milliseconds, look at the performance counters to see which ends up with more instructions executed, and then move the task to where it performs best.

From time to time, it can retry the test, because software frequently changes what it spends time doing.

Re: AMD releases a new flagship CPU for consumer market with 128M of L3 Cache

#105
post #41

Earlier quoted context omitted.

I vaguely remember that the iGPUs in the 7000 series had some trouble with Linux support. May be wrong, but do look into that. Might need a bleeding-edge kernel and mesa.

There was a blog post posted here a few weeks/months(?) ago but basically the person was using an old kernel. I'll look more into it.

This is a recurring theme with AMD, going back to (at least?) the Zen 1 APUs.

Initial linux support is buggy, and you basically have to run a bleeding edge kernel.

Re: AMD releases a new flagship CPU for consumer market with 128M of L3 Cache

#106
post #86

Silly question: what constrains cache sizes? What prevents just making them bigger and bigger?

SRAM burns more power and uses more die space than DRAM Some do make them bigger and bigger, like the whole-die cerebras AI chip.

That's only partially true.

SRAM doesn't need to be refreshed constantly like DRAM, so SRAM will use LESS power when not switching. We think it's different because something like L1 cache is CONSTANTLY switching. It should be noted that the power cost per GB still isn't worse than DRAM, but there's way more data being transferred.

Once you reach L3/L4 cache, it's not switching nearly as often and the actual total power becomes way less than sending data over from RAM. This is one reason why AMD (and now Nvidia) saved so much power with Infinity Cache on RDNA 2.

The big issue with SRAM is that it requires 6 transistors per bit while DRAM requires 1 bit plus 1 capacitor, so capacity per mm2 of die area is much worse. That capacitor keeps thing cheap, but is also the reason why individual DRAM cells can only operate at 300-500MHz while SRAM can easily operate into the many GHz range.

Re: AMD releases a new flagship CPU for consumer market with 128M of L3 Cache

#107

Earlier quoted context omitted.

Its more of a fundamental scheduling issue. The unlike big/little cores OS has no idea what apps "prefer" cache or frequency.

An OS can easily run an app on each for a few milliseconds, look at the performance counters to see which ends up with more instructions executed, and then move the task to where it performs best. From time to time, it can retry the test, because software frequently changes what it spends time doing.

But apps like factorio are extremely dynamic, so thats either going to be flakey or its going to spend a lot of time/energy bouncing the process between cores.

I wouldn't be too worried about this personally, as configuring the few really sensitive apps with ProcessLasso or Aniancy is pretty easy.

Re: AMD releases a new flagship CPU for consumer market with 128M of L3 Cache

#108
post #18

The inflation has really hit the consumer market... 700$ for CPU and over thousand for GPU... Memory is not cheap either... Not that it won't sell, but still these price points for something still called consumer start to be high. You could get a whole portable PC for same money.

$700 topish tier CPUs are nothing new. The Pentium 4 Extreme Edition had a $1000 MSRP for instance. Even in 2004 you could get an entire laptop for the money, even an Apple laptop with the base model iBook G4 selling for $1000. There is still good CPUs in the $100-$300 range. GPU prices have gone insane though with mid-range having somehow moved up to $400-$500 where high-end was a decade ago.

The GPU market is definitely suffering from having only one dominant player. I'm hoping that AMD is able to invest some of the extra cash flow since the introduction of Ryzen toward making their GPUs fully competitive with NVIDIA rather than having to play catch up all the time. Also, NVIDIA kind of has to price gouge on this generation because they made so much money during COVID and the crypto boom. Unless they want to be like Zoom or Peloton and lose 75+% of their market cap, they have to keep the profit curve from plunging. And they know there's latent demand from gamers who were priced out of the market before, plus pretty strong interest from the AI side, so why not keep the prices high to maximize profit?

I also think another factor in the rise of GPU prices is how quickly things have been moving on the display front. Not only did we go more or less directly from 1080p to 4K, thereby quadrupling resolution, now we're not shooting for 30 or even 60 fps minimums anymore. We want 1% lows to be above 120, 144, or even 240fps so that our high refresh rate monitors are properly fed. Oh, and we don't want to turn down image quality while doing it. Now throw in VR, where high-end headsets can be 4K or more per eye, and you've got a lot of pixels to push. So top-end GPUs have to be these behemoths with several kg of cooling hanging off of them, because they are now the biggest power consumer in the system. Yet they still have to fit into the real estate allotted to just a few peripheral slots, usually in an orientation that's not optimal for airflow. It's quite the engineering challenge, and I kind of see why GPUs at every level have gotten so expensive, since they're all priced relative to the top range.

Re: AMD releases a new flagship CPU for consumer market with 128M of L3 Cache

#109
post #93

Earlier quoted context omitted.

Or just buy the X3D that have cache on each CCD instead of half of them.

More precisely, buy the X3D that has only one CCD. There is currently no consumer model with 2 CCDs and X3D on both of them.

Right, so the 7800X3D (due in April), the old 5800X3D, or any future threadripper or Epycs with the X3D.

Best L3 per core outside of the X3Ds it the 7600 or or 7900 CPUs that come with the full size L3 (32mb PER ccd) but only 6 cores per CCD (instead of 8).

Re: AMD releases a new flagship CPU for consumer market with 128M of L3 Cache

#110
Lots of software could run in just 128MiB, especially if it could page stuff out to ssd.

CPU's usually have a cache-as-ram mode that can enable this.

Does this mean that systems where you can hot swap all the ram at once will be possible?

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