AMD - Piledriver chitchat

[kalniel]

Also, reviews of the 285 are starting to trickle out, seems a bit meh overall. Granted, it offers new features and driver optimisations might improve performance further, but it's pretty much the same as the 280 it replaces in performance, and around the same area in terms of power efficiency. The fact all the reviews I've seen so far seem to be testing OC models probably isn't helping efficiency though.

Tech Report seem impressed with it, especially in their 'bad frames' measure compared to the 280 (which I prefer over average fps). They also hint that there may be room for beefier versions to come.

[watercooled]

I was just expecting a bit more given the marketing noise. I mean there's no reason you'd avoid it if you were in the market for that sort of price range, it just doesn't seem to have much to shout about ATM. Again though, some of the arch and feature changes might differentiate it more over time.

But yeah, given the transistor count I think it's pretty much guaranteed we'll see an X version soon.

[kalniel]

Tahiti/Pitcairn are DX12, but won't work with FreeSync

http://techreport.com/news/27000/amd...esync-displays

This is disappointing - I'll have to upgrade regardless if I want a synced monitor, so the market gets thrown open again.

I wonder if AMD are waiting to see how nVidia position their new Maxwells before releasing the 285X - then they'll set clocks/pricing accordingly to beat it by some measure (either performance or value).

[CAT-THE-FIFTH]

Some more info about the newest FX8300 series from The Stilt(famous CPU overclocker):

http://www.xtremesystems.org/forums/...=1#post5237937

So it is finally the second of September...

So far I have posted a picture of a crown (which once belonged king George XII of Georgia) and hashtags #kg & #Alphabet...

#kg which stands for Kilogram
#Alphabet... "Kilo" stands for "K" in the phonetic alphabet

So what is this all about?

Everything below is highly unofficial of course as is everything else I write here.

Piledriver module based Vishera die has been mass-produced in two different die revisions since the prototyping phase.
While all of the revisions have the same major die version (OR-C0), the minor revision has changed.
Initially the first mass-produced die revision was "India" (OR-C0i, prototype and ES only), the second revision was and still is "Juliett" (OR-C0j, retail) and now finally...
The "Kilo" revision (OR-C0k) a.k.a "King Vishera" a.k.a "Vishera Type-K" has arrived.

The "King Vishera" is initially only available in the new models, FX-8370E & FX-8370.
This is most likely the case with FX-8320E also, however I have not been able to test one of them personally.
The new version is likely to be phased-in at least in the other high-end models such as FX-9590 and at some point in all of the remaining models also.
The alledged metal tapeout of the new revision (alledgedly) occured in the beginning of July. So the only way to get a newer revision part is to get one of the new models, atleast in the beginning.

The differences?

- On average 18% less leakage*1 (0-38%) for FX-8370
- On average 53% less leakage*1 (14-106%) for FX-8370E
- Up to 300MHz higher overclocking margin *12
- 100mV less voltage required for the same clocks on average *1

*1 - Compared to an average FX-8320 or FX-8350 CPU
*2 - When not restricted by the cooling or the motherboard (VRM)

The E-version is the best choice for air or water cooling thanks to the ultra low leakage characteristics.
The non E-version does the same clocks however it might require use of a higher end motherboard (with better VRM) and high-performance cooling.
The non E-version has significantly better overclockability under sub-zero temperatures (phase, LN2) since the leakage levels of the E-version are too low for the purpose.
Having an ultra low leakage characteristics is great under normal conditions however under sub-zero temperatures the voltage requirements become a issue.
Basically the low leakage part exhaust the usable range of supply voltage prior reaching it's maximum frequency.

Based on my own tests, I would estimate that >95% of FX-8370 & FX-8370E parts will reach 4.8GHz frequency in 24/7 without a custom watercooling or a ultra high-end motherboard being a requirement.
As long as the temperature (see below) stays =<65 degree C or 149 degree F and the motherboard has even remotely a sufficient VRM you'll be fine.

On a high-end motherboard and a custom watercooling 5.0G - 5.2GHz+ should be doable in 24/7 use with a good specimen.

These chips still draws a vast amount of power when overclocked so the final overclocking potential is basically just the matter of cooling.
The maximum recommended temperature during the worst case stress is 65?C tCase.

Officially the maximum tCase temperature for the various FX models is specified to:

Infra A - FR (125W TDP) - 61.1 degree C
Infra B - WM (95W TDP) - 70.5 degree C
Infra C - OL (65W TDP) - 70.3 degree C
Infra D - HO (45W TDP) - 69.1 degree C
Infra E - SJ (25W TDP) - 70.0 degree C
Infra F - FH (220W TDP) - 57.0 degree C

The tCase temperature must not be mixed with the tCTL control value sometimes dubbed as the "package temperature".
The tCase temperature is also calculated and it represents the simulated case temperature, measured from the very center of the heatspreader (see the illustration).
Neither tCase or tCTL is the actual die temperature. The actual die temperature information is not directly available on these processors. The actual die temperature is significantly higher
than the tCase or the tCTL control value indicates.



The maximum tCTL control value on all of the FX-series processors is 70 units.
When that value is reached the processor HTC logic engages and starts to reduce the power consumption and dissipation by throttling.
Some of the motherboard manufacturers (such as ASUS) alter the limit manually to reduce the chance for throttling.

So when you are talking about the temperature always use the tCase temperature instead of the tCTL control value.

Here is the examples of the wrong and right values in various monitoring softwares.

Red = Wrong (tCTL)
Green = Right (tCase)









The AOD picture also explains the value dubbed as "Thermal Margin".

Also here is a reminder why Prime95 should not be used as a reference for stability when overclocked. It results significantly higher power draw and emitted thermal than any of the most stressful real world applications.If you still find it absolutely necessary to use Prime95 for stability testing please do it this way:

Run it on only two compute units at once (set the thread count to 4 and affinity accordingly) and decrease the cooling to simulate higher power dissipation.

Only the relative Stock or OC results are comparable.

BTW,some of the R9 285 reviews peg the GPU as having significantly lower power consumption than the R9 280 and others indicate similar power consumption.

However it seems the Tonga GPU is 5 billion transistors(which is more than Tahiti) and is around the same size.

This might indicate the GPU has some more fused off functionality IMHO.

[watercooled]

Interesting stuff!

In regards to the 285, yeah I've seen some sites claiming lower power whereas some it's higher than the 280X. Like I touched on earlier it might be largely dependent on OC/non-OC and voltages used.

However it is impressive they've managed to get close performance with a much narrower memory interface, but as mentioned on the TR article, it could be very interesting if there's actually a 384b interface on-die.

[watercooled]

Some numbers from a less-overclocked card: http://ht4u.net/reviews/2014/amds_to...st/index17.php

Edit: And another: http://hothardware.com/Reviews/AMD-R...rrives/?page=9

[watercooled]

Woah hang on a minute. I've just sat down and gone back through some of the 285 reviews I looked at earlier; I think I've just skipped through and looked at the Crysis FPS and not much else. I think I've had a preconceived notion of where performance would be, saw one or two numbers to back it up and accepted it then gone to look at power numbers to compare efficiency. :facepalm:

In some other games it's matching/exceeding a 280X and 770! I wonder if that extra tessellation performance could mean less of a performance impact vs Tahiti when it's enabled in games like Batman for example?

Edit: Found some tessellation benchmarks here: http://www.computerbase.de/2014-09/a...benchmarks/12/

[DanceswithUnix]

Thought I would enjoy reading the Anandtech article about the new MIPS cpu.

But then they give a quick background of threaded CPUs, getting it about as wrong as possible.

http://www.anandtech.com/show/8457/m...ture-arrives/3

Forgets the early work in the Tera (later Cray) MTA, the fact that IBM implementation predated the Intel one by years, forgets the old unreleased Alpha cpu & ignores SPARC. So although Intel were late to the game they are held up as pioneers. Just sad.

[Noxvayl]

Thats what bias is all about, preferential treatment for those currently seen as the leaders but were far from pioneers when the technology was first invented. Intel are a great chameleon corporation, take on other people's inventions and make them their own very well; much like bull****ters being most popular at school but end up failing when they leave, more often than not anyway.

Oh well, better put the Intel hatred back in the bottle, it seems to be growing in strength recently.

[watercooled]

Remember this?

I wonder if that >350mm2 is referring to Tonga?

[watercooled]

According to SA, Haswell-EP 18C is 662mm2. Tis a big'un!

[CAT-THE-FIFTH]

Remember this?

I wonder if that >350mm2 is referring to Tonga?

You mean an R9 285X with 2048 shaders and a HBM memory??

[watercooled]

I mean if Tonga is the >350mm2 part it's referring to, I wonder what the >500mm2 part is?

Although it would make sense for the Tonga die to have 2048 shaders on-board. Dunno about HBM though, it doesn't seem like a bandwidth-strangled die anyway.

[scaryjim]

I mean if Tonga is the >350mm2 part it's referring to, I wonder what the >500mm2 part is? ...

Hmm, good catch - Hawaii was only 438mm² if the reviews are to believed. Then again, would AMD be farming out design to third parties at this stage? Where did that slide come from? Too many questions!!!

[watercooled]

I'm not sure what part of the design/testing they're involved in but quite a few big IC companies seem to employ them: http://www.synapse-da.com/Corporate/Clients

I seem to remember reading that Nvidia were a client in the past, but don't quote me on that.

[scaryjim]

Hmmm, interesting stuff. of course, if NV were a client the 500mm² die could be one of theirs.... OTOH it could be a genuinely monster AMD chip, or it could be an earlier design of Hawaii before they redesigned the memory interface to bring the die size down perhaps? Lots of possibilities....

if it is a currently unreleased AMD graphics die, it'll have well over 3000 shaders....