Were those 780Ti clocks? The author was carefully vague....
There has to be a reason why AMD is using those coolers. Maybe they are sitting on shedloads of stock, or have some deal with whatever company provides them for x amount of years?
Whatever, they've shot themselves in the foot yet again. Such needless hassle over a simple part, and they could easily have charged $50 more with a better one. Instead they've basically snatched a draw from the jaws of victory.
AMD does not officially specify a base clockspeed (or a TDP for that matter). Those numbers are taken from turning down the fan speed limit and hitting the card with FurMark; the card will drop to its base clockspeed and then override the fan maximum to keep it there.http://forums.anandtech.com/showpost.php?p=35699215&postcount=24
And incidentally, Ryan Smith reports the base clockspeed of the 290 as 662 MHz. Whether or not that's in the official documentation I have no idea. "Up to" marketing is misleading, I'll give you that.
Yes, you're right.The turbo functionality introduced with Kepler is where at least some of the leeway was exploited.
But the capacity of heat sink must be the biggest factor. And that's something that may vary quite a bit due to variances in manufacturing, assembly, and, of course, usage of third party coolers. That is not something you can model by collecting the toggle rate of various units across the chip. (Well, you could create such a model, I guess, by correlating toggle rates with observed temperatures? Let's assume they don't do that. )The thermal diodes used to feed into typical monitoring software measure ramps on the order of significant fractions of a second. That's a value modified by the thermal capacity of the heat sink, the imprecision of the diodes, and conduction across the GPU over a pretty long period of time.
But that's still a 3 orders of magnitudes larger than the microseconds' granularity to regulate voltage.The instantaneous power draw and localized heating for spots in the logic can go up and down more quickly, particularly if other elements like fan speed ramp or cooler quality are constrained. This may not be a particularly close proxy, given its age, but for a modeled CPU in an era of lower power density, there are localized temperature ramps that happen in hundredths of a second. There's an example of a 5-10 degree ramp that is basically over in .1 seconds.
Probably a GTX780. And according to their review, the 290X still beats the 780 on average with the 40% fan profile (with the lower clocks shown there). The clock speed may be lower, but it is still faster. With better cooling (or more noise with the 55% fan profile) it decisively beats the 780. I wouldn't read much into the drop of clock speed for the 290X (which shows, that there is a lot of headroom with a more capable cooler) other than one has to be very aware of the individual environment one puts the card into (to a larger degree than it's the case also with an nV GPU) to not get surprised by the resulting performance difference to reviews.Were those 780Ti clocks? The author was carefully vague....
While the metal enclosure may help a bit (but it is not directly connected to the actual cooling surface, so it's probably a small effect), I think it's mostly the fan itself. It is slightly higher (I think the VRM cooling is done differently saving a few millimeters height for the baseplate which can then be used for the fan). That means it needs a lower speed for the same throughput. Furthermore, it looks like they optimized the number and angle of the fan blades. It uses more blades at a slightly lower angle, but no idea how much difference this makes compared to the higher fan height. But it looks like the AMD design keeps the VRMs cooler in exchange. But the added noise is a fairly large sacrifice for thatIm curious.... what makes Nvidia stock cooler that much better? Looks the same-sized vapor chambered centrifugal blower design? Does the metal enclosure helps that much...? Amd is even using some special thermal pad iirc....are we sure its not just poor leaky bins?
Were those 780Ti clocks? The author was carefully vague....
THG hints at AMD preparing a >US$550 answer to Nvidia' upcoming GTX 780 Ti, essentially a 290X with a better cooler and presumably higher clocks. If this is true, whether it will be a new SKU or simply recommendations to AMD's partners for their factory overclocked configurations remains to be seen.
http://www.tomshardware.com/reviews/radeon-r9-290-review-benchmark,3659-2.html
Incidentally that was a very good article and everyone should be taking note. The advertised clock speeds of the 290 cards are flat out misleading. A system of base clock + typical boost like NV would be much more informative.
Have to admit it's an atrocious release for AMD. It looks like a potentially fantastic GPU especially for the price but all the initial issues with review samples and throttling could really put a damper on their initial sales boost.
As long as reviewers inform themselves properly and avoid publishing numbers from "cold" cards the advertised speed discrepancy is less of a problem.
My bigger concern is (as stated in the article) how 3rd parties could abuse the "up to" rating. We may not have the luxury of benchmarks of GPU's from 3rd parties so what's stopping them putting a different (but no better) cooling solution on their card, upping the max speed to 1100Mhz in the bios but never actually achieving better speeds than the reference 290x outside of the first 5 minutes of gaming?
Reviews? If events of the last few days have taught us anything it should be that we'll see a lot more in-depth cooler data.
Does AMD allow partners to go above 10% on overclocks yet anyway? Or is it a timed thing, ie no 10%+ overclocks for the first 6 months? I remember reading something to that effect a while ago.
Tackling this in reverse order, there should be some correlating between event counters and temperatures. If not at run time, it would be part of the power estimation engine, which estimates power based on event counters and values that are derived from physical characterization of the device. I think the latest versions of that include a temperature factor.But the capacity of heat sink must be the biggest factor. And that's something that may vary quite a bit due to variances in manufacturing, assembly, and, of course, usage of third party coolers. That is not something you can model by collecting the toggle rate of various units across the chip. (Well, you could create such a model, I guess, by correlating toggle rates with observed temperatures? Let's assume they don't do that. )
It would allow the GPU to take a bite into the voltage guard-banding, since it can respond more quickly to demand variations that could cause voltage to drop for a few milliseconds.But that's still a 3 orders of magnitudes larger than the microseconds' granularity to regulate voltage.
It might be more proactive, or it could if AMD's CPU turbo has any indication.I'm trying to see how this typically would work:
- some unit gets a burst of activity
- this raises an alarm of potential localized critical temperature
- lower voltage by a few mV?
- lower clocks all across the die as well because of slower transistor switching speed. (I'm assuming that this will lower the voltage across the whole die.)
That would be a more CPU-like thing to do, looking at the P4's duty cycles or things like Foxton. GPU DVFS is still inferior to CPUs. Hawaii is just not insanely inferior.Voltage is a very big hammer to play with, and normally used at the macro level. If you're concerned about local temperatures, wouldn't it make more sense to have some clock pulse dropping mechanism at the smaller unit level? This way, you get very granular control and don't impact the whole die.
It can shave off voltage margins that need to absorb demand spikes, which are worsened by variable clocks. Otherwise, a more conservative voltage has to be selected for most of the time it's not needed, or activity has to be scaled back. The clock/voltage choices become far more limited like they are with Kepler.Maybe they already have that, but then, again, that raises the question of how much additional benefit you get by furiously regulating voltage.