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UPDATE: Adding more explanations from AMD.

Contemporary microprocessors from AMD and Intel can dynamically change their clock-speeds in order to reduce power consumption or improve performance. Still, there are certain clock-speeds that are declared to be default and at which the chips should operate most of the time in all applications. However, it looks like under certain conditions AMD’s latest microprocessors for desktops run at lower clock-speeds, which negatively affects performance.

AMD’s latest A-series accelerated processing units code-named Trinity have default clock-speeds, idle clock-speeds as well as maximum clock-speeds that are activated only in certain cases and when the Turbo Core technology in enabled. However, it was discovered in the “Contemporary APUs: AMD Trinity vs. Intel Ivy Bridge” article, under high multi-threaded loads, Trinity drops clock-speed below base levels. For example, AMD A10-5800K APU has a base clock rate of 3.8GHz and capable of turbo-boosting to 4.2GHz, however, at high multithreaded loads the clock-speed is dropped to 3.40GHz, not to 3.80GHz as the processor’s TDP exceeds the default level. Other Trinity microprocessors behave in similar way.

During the test of AMD Trinity APUs, X-bit labs observed stable drop of clock-speed in Linpack benchmark and irregular drops in various video encoding apps, 3D renderers, etc. It is interesting to noted that the frequency never drops when Turbo Core is disabled and the processor operates at 3.80GHz all the time. As it turns out, in certain cases AMD’s chips deliver lower performance than they are supposed to.

AMD appears to know about the decrease of clock-speed below the base level and claims that it occurs in very rare cases under loads that are not typical for client microprocessors.

“Linpack is one of the few synthetic applications that may exceed the de-rating defined for our TDP. In the synthetic instances where base frequency causes our APU to run above its TDP, the part will throttle down to a frequency below base. Similar to Intel, thermal design power (TDP) is a realistic power target for partners to use in order to provide the best balance between cost and performance.  However, as stated above, some unusual and synthetic workloads can cause a thermal event where our APU briefly drops below the base frequency,” said Peter Amos, a spokesman for AMD.

The world’s second largest maker of PC microprocessor also does not consider the drop of clock-speed below the officially stated level a problem, but believes it is a good design decision.

“Trinity-based APUs use workload calculations to set frequency and protect the processor. There are some benchmarking apps that trigger the extreme of those calculations. In this case the APU hits the max for a split second, reduces frequency before jumping up, and repeats this pattern until temps improve. When TDP is exceeded, graceful clock throttling via the Turbo Core technology is a designed defense to protect the processor. By design, the clocks may be throttled even below the base frequency when worst-case high-power applications (non-typical to market segment e.g. HPC app in this case) are run. In other words, base frequency is designed such that it is sustainable (i.e. APU operating at or above base) for most, if not all, typical applications relevant for the market segment. […] It would be a problem and unfair if these “tests” ended up ruining the life span of our customers’ products,” concluded Mr. Amos.

Tags: AMD, Fusion, Trinity, 32nm, Piledriver, Radeon, ATI

Discussion

Comments currently: 26
Discussion started: 04/01/13 07:44:03 PM
Latest comment: 08/30/13 03:56:30 PM
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1. 
This is no big deal IMO. Most folks never use a CPU/APU @100% load for any length of time so for the most part the CPU/APU runs at the default frequency or higher. Unless all you do is run stress testing 24/7 or max out the TDP, the change in frequency is moot.

As noted you can disable Turbo mode and the frequency runs fixed so it's really a non-issue.It's worth noting that with most mobos the VRM circuit has a thermal safety that cuts in and drops the Vcore and frequency so this is often the limiting factor, not the CPU/APU itself.
8 6 [Posted by: beenthere  | Date: 04/01/13 07:44:03 PM]
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show the post
4 7 [Posted by: kailrusha  | Date: 04/01/13 10:25:27 PM]
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I guess when you combine a powerful CPU and GPU together in a HSA SoC, it's going to get hot. I'm sure Intel will experience the same problem once its GPUs become sufficiently powerful. The question is whether AMD is being misleading in their performance figures. I don't think so myself. Obviously the APU is going to reach its TDP envelope quicker when it runs overclocked in turbo mode with a stock heatsink. CPUs are usually throttled by the BIOS when they've reached a critical temperature. There is nothing sinister here. At least with this AMD technology, the APU is not being throttled to 50% or worse, frying. The solution of course is to simply use an after market heatsink.
9 3 [Posted by: linuxlowdown  | Date: 04/01/13 11:26:39 PM]
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I agree, lets wait for 22nm from AMD im sure it will get faster and Better
6 3 [Posted by: xentar  | Date: 04/02/13 02:42:35 AM]
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2. 
1 April news, i dont know what to believe anymore
7 0 [Posted by: soryuuha  | Date: 04/01/13 07:59:50 PM]
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No, the April Fool's Day news was -

1) Intel approaches NVIDIA CEO Mr Huang to become Intel CEO.

2) Apple issues an apology to its customers.
8 2 [Posted by: linuxlowdown  | Date: 04/01/13 11:44:17 PM]
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3. 
How is this news? It's like the thermal throttling that all CPU's experience as they exceed their temp/voltage
3 1 [Posted by: Stickmansam  | Date: 04/01/13 10:00:11 PM]
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Not all, but Intel CPUs and if thermal throttling is enabled in BIOS.

New here is that it happens without user's consent and not according to specification.
2 1 [Posted by: KonradK  | Date: 04/02/13 01:20:26 AM]
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The problem is: they can't deliver even base freq w/o overheating. Not OC, just base freq written on BOX. And I tested this with BOXED APU, i.e., with APU + native fan. Hence, product that was sold to me doesn't meet advertised specification. That is the problem, not thermal throttling per se.
0 0 [Posted by: Raistmer  | Date: 08/30/13 03:56:30 PM]
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4. 
This was known from quite a while ago. At least for BD/PD chips. So one would guess it applies to APUs as well. For laptops I would definitely call it a feature, since capping the power draw IS desirable. For desktops not so, but these companies have learned to care less and less about maximizing desktop performance.

But of course, even if undesirable, one would probably not notice the performance decrease. If he or she does, than the BIOS settings disabling this behavior may be turned on. So a non-issue, really.
2 2 [Posted by: entity279  | Date: 04/02/13 12:50:10 AM]
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5. 
So basically AMD is running too high of a factory overclock to make their chips look better on paper. If Intel did this, AMD fanboys would be tripping over themselves in protest. AMD does it and they get a pass judging by the comments here.
7 7 [Posted by: AnonymousGuy  | Date: 04/02/13 02:36:47 AM]
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No dude. In 99% of cases, there is no problem with the overclock. So the overwhelming majority of people get a faster AMD APU, increasing their productivity. This overclock is therefore justified.
6 2 [Posted by: linuxlowdown  | Date: 04/02/13 05:13:18 AM]
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6. 
With such a small throttling, only under very limited circumstance(Linpack does not represent realistic usage, especially not for an APU), i have major trouble feeling annoyed at it.

What i do NOT like however is that AMD now has joined Intel in the darned "use TDP not real wattage" club. Even if it requires unrealistic usage to make it go above TDP, it´s still a bad thing.
5 0 [Posted by: DIREWOLF75  | Date: 04/02/13 04:52:30 AM]
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7. 
I have an AMD APU, and kinda witnessed this and i thought it was smart feature, to avoid the CPU from burning it selt, AMD throttle down, so what !!!.

Besides Turbo core = factory set Dynamic overclocking, for maximum stability all users should disable AMD Turbo, however if you want max performance keep it on, its just like RAM DDR3 1866 and DDR3 1333, for max stability grab the 1333, but if you want performance and some irregularities grab the 1866.

4 4 [Posted by: medo  | Date: 04/02/13 06:48:08 AM]
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No, you don't sell a product and then say if you want it to work all the time turn things off.
2 2 [Posted by: KeyBoardG  | Date: 04/02/13 01:55:19 PM]
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I would agree with this : if the box says 3.8ghz. it aught to run that speed 100% of the time without fail, to say otherwise would put the box and advert false. now if it is a cooling issue... then shame them again for relying on the end user to 'properly cool' a retail purchase.
2 2 [Posted by: amdzorz  | Date: 04/02/13 02:18:36 PM]
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8. 
Hahahahaha... lol what!?? My Thuban does not do this? It's overclocked to 4ghz... nor does my athlonx4 media pc... nor does my 5ghz Sandy. I hope that 'feature' can be turned off with proper cooling otherwise encoders, folders and modders will avoid this like the plague.

1 3 [Posted by: amdzorz  | Date: 04/02/13 09:25:45 AM]
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AMD's turbo works off of actual thermal readings so better cooling = more turboing (with caveats I'm sure).
4 0 [Posted by: mikato  | Date: 04/02/13 01:06:44 PM]
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9. 
I dont se a problem there, it is 2013 and not 1999, and we have more than one clock speed on cpu. But we know that already, did we.

There is a default clock lets say 3.8ghz,there is single tread clock or single module clock lets say 4.2ghz and there is idle clock something like 1.4ghz, and suprisingly there is full load clock witch is, lets say 3.4ghz.

Stil dont see problem there.
1 1 [Posted by: kingpin  | Date: 04/02/13 06:10:56 PM]
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10. 
When the going get tough, the ...don't go.
0 0 [Posted by: Tukee44  | Date: 04/02/13 08:45:47 PM]
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11. 

I would say it's quite disgusting move from AMD. They write particular freq on box. They can't deliver that freq then. So? They just lied about real APU performance.
And I see these freq drops on my everyday app, not on just synthetic tests!
0 0 [Posted by: Raistmer  | Date: 08/30/13 03:52:15 PM]
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