AMD's Phenom X4 9950, 9350e and 9150e: Lower Prices, Voltage Tricks and Strange Behavior
by Anand Lal Shimpi & Gary Key on July 1, 2008 12:00 AM EST- Posted in
- CPUs
Final Words
Overall, the conclusion here isn't too much different from the Phenom re-launch and the X3 reviews: AMD's CPU division is finally competitive again. The return to competition isn't because of an increase in performance or architectural changes, it's simply through very aggressive pricing.
The Phenom X4 9950 BE and 9850 BE are reasonably competitive with the Q9300 and Q6600, although we would still opt for the Intel solutions thanks to lower power consumption and significantly better overclocking potential. Gaming performance continues to be a strength of Intel's as well.
The Phenom X4 9550 is the sweet spot of AMD's product line and it does do well against Intel's dual-core E8400, as do the X3 8650/8450 against Intel's E7200. As we've shown in the past however, take overclocking or power consumption into consideration and Intel is the clear choice. Unlike AMD's GPU strategy however, AMD does not have a higher end CPU strategy; get beyond the Q9300 and AMD no longer has an answer to Intel's quad-core lineup.
Now it's time to talk about the new energy-efficient quad core chips. While AMD likes to talk about the 9350e and 9150e as both being things that Intel doesn't have (65W quad-core), the two just aren't worth it. Based on the price cuts, AMD's Phenom X4 9350e makes absolutely no sense. You can get nearly the same system power consumption using an underclocked, undervolted Phenom X4 9550 and save $20. The same goes for the 9150e, you can achieve the same thing using a 9550 and the two cost the same amount. The new "e" processors appear to be nothing more than a way of rebadging AMD's leftovers, the 9350e and 9150e just aren't worth the premium.
It's also worth addressing the issues we've encountered with motherboards in the testing for this article. With AMD pushing TDPs of over 100W on many of its Phenom processors, we definitely need better quality components on even mainstream motherboards. As we saw in our testing, even without overclocking the 9850BE caused us some problems on our 780G test platform.
Then there's the business angle. It's quite possible that a user would want to put a very high end CPU in a motherboard with integrated graphics, if they have no desire to play 3D games. The problems we've encountered with both AMD and NVIDIA based IGP Socket-AM2+ motherboards have shown us that such a combination isn't always reliable. The problem gets worse when you realize that many of these motherboards are certified for use with 125W TDP chips, although they are unable to guarantee 100% reliability with them.
Even enabling support for the 140W 9950BE gave us some problems on our 790FX test platform, although not nearly as much as getting a 125W chip to work on our 780G board.
Furthermore it's very tough to say what will come of the Cool'n'Quiet issues we've outlined here today. Even as I write these lines, Derek is sitting next to me and encountering similarly erratic Phenom performance with CnQ. We will continue to work with AMD on figuring out what's going on with CnQ, but until then it's tough to draw any real conclusions.
In the end, overclocking and CnQ issues aside, AMD's latest price cuts do ensure that the Phenom is a viable second choice alternative to Intel's Core 2 Duo and Quad lines. Unfortunately unlike AMD's successes on the graphics side, it's not enough to dethrone the king. We want a Radeon HD 4800 from the CPU division, but instead we've gotten something more along the lines of a 3800. It's good, but not good enough.
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MikeODanyurs - Thursday, July 17, 2008 - link
This article got me thinking, why would you purchase a 9350e for a HTPC (which was what I was planning) when for the same or less money, you could get a 9850 Black Edition and just set the muliplyer to 10 (instead of 12.5). You'd have a CPU that you could use later on at full speed or OC'd, but for now on a HTPC underclock it to the 9350e speed and you would still have the bus at 4000 (not 3600) and the NB and HT speed at 2.0GHz (not 1.8GHz). Anything I would like to know is what the power usage would be if you did this (125w), compared to a 9350e (65w).Wwhat - Friday, July 11, 2008 - link
In regards to your description of the strange behavior I'd like to point you to this article on microsoft.com:http://support.microsoft.com/?id=896256">http://support.microsoft.com/?id=896256
An excerpt:
Possible decrease in performance during demand-based switching
Demand-Based Switching (DBS) is the use of ACPI processor performance states (dynamic voltage and frequency scaling) in response to system workloads. Windows XP processor power management implements DBS by using the adaptive processor throttling policy. This policy dynamically and automatically adjusts the processor’s current performance state in response to system CPU use without user intervention.
When single-threaded workloads run on multiprocessor systems that include dual-core configurations, the workloads may migrate across available CPU cores. This behavior is a natural artifact of how Windows schedules work across available CPU resources. However, on systems that have processor performance states that run with the adaptive processor throttling policy, this thread migration may cause the Windows kernel power manager to incorrectly calculate the optimal target performance state for the processor. This behavior occurs because an individual processor core, logical or physical, may appear to be less busy than the whole processor package actually is. On performance benchmarks that use single-threaded workloads, you may see this artifact in decreased performance results or in a high degree of variance between successive runs of identical benchmark tests.
..
It also explains how to change the policy in windows regarding this behavior, and while this is about XP I would not be surprised vista inherited this.
Rev1 - Saturday, July 5, 2008 - link
I dunno im gunna wait till nahalem comes out.gochichi - Thursday, July 3, 2008 - link
I see that they have a lot of issues still. They need make sure that their board partners and chipset designs are really stable and ready for the "future"... I thought that was the whole point of AMD's spider platform, that they weren't gonna be playing around with switching sockets on users and such.Well, anyway... I love having a quad-core (Intel) and I think that these products are all at a nice performance level. I do believe it helps for them to have ATI right now. Because if I were going to buy a cross-fire system, which I think makes more sense now than at any other point of time, it would be tempting (though still ultimately wrong) to get a 2.5 AMD quad-core to have everything match.
Wow, it's a great time to be a computer shopper right now. Today's AMD would have trounced yesterday's Intel, but Intel is just so lean and so efficiently producing better and better stuff that it's a tall order to even compete. AMD does seem to be making their appeals to the big guys pretty effectively, seems like when you go to brick and mortar stores about half of the systems are AMD based.
Looking into the future, AMD has what it takes to remain relevant in the market. They need to switch to a smaller process and save energy, and keep the 3 or 4 core thing going... no dual cores at all is the right thing to do.
I'm thinking that AMD could really grow into a huge beast with their AMD/ATI combo, just look at the beating NVIDIA is getting all of a sudden. The Radeon 4850 is going for $170.00??? And it's in abundant supply... wow, sucks to be lil' NVIDIA right now. AMD beat Intel when Intel was doing all kinds of illegal stuff that made it irrelevant, next time AMD beats Intel (if) it's going to be a very very big deal.
AMD has market share and name recognition, all they need now is a killer product, and I think they're getting really close to having one.
Aries1470 - Thursday, July 3, 2008 - link
Hey, just speculating now...
In a couple of years (maybe some time next year?), we should start seeing CPU's incorporating GPU's, or vice versa.
So the battle would be something like:
AMD/ATI
Intel/Intel
VIA/S3 Hey, they are still on single cores, as far as I know, but they do have the Chrome 440 GTX, of which is a DX10.1 product, but that doesn't mean much.. I haven't searched for a review yet ;-)
nVidea/??? correct me if I am wrong, but at the moment they have No rights for x86 CPU??
Well, that is my 2¢ worth.
p.s. the Chrome 440GTX is with a 64bit memory us? Hmm... not really wide. ahmmm...
Calin - Friday, July 4, 2008 - link
VIA is playing in a league of its own (or played, until the Intel Atom). Even with the Atom, the northbridge is using a lot of power, so VIA could still compete.VIA is now all about integrated platform with low performance at very low power draws (very low compared to the x86 world of today).
As for the 64-bitness of the S3 Chrome memory controller, this too helps save both costs and power.
garydale - Thursday, July 3, 2008 - link
I realize that the Windows world is still 32bit, but we're talking about processors here. I run a pure 64 bit Linux (Debian/Lenny) with (almost) no 32 bit applications - certainly not the ones I use frequently that need full processor speed. Why are the tests all done with 32 bit software?Even if you can't run all the tests in 64 bit mode, surely a few benchmarks are available in 64 bit so we can get an idea of how the various processors perform in their native modes?
ohodownload - Wednesday, July 2, 2008 - link
- The AMD Phenom X4 9950 Black Edition 2.6GHz @ 140W; $235
- Energy-efficient AMD Phenom X4 9350e 2.0GHz @ 65W; $195
- Energy-efficient AMD Phenom X4 9150e 1.8GHz @ 65W; $175
The first thing to notice is that AMD is launching a new model set 100 MHz higher for the same price as the previous 9850 at 2.5 GHz. The small boost in frequency should enable this CPU to be equivalent to Intel’s Q6600. Unfortunately, this is to the detriment of power consumption and the TDP gains 15W compared to the previous model for a total of 140W. Therefore, even with its Q6600 Intel holds a clear advantage in terms of power consumption all the while being slightly less expensive (officially $224)....
more : computer-hardware-zone.blogspot.com/2008/07/new-3-amd-phenom-x4s.html
aguilpa1 - Wednesday, July 2, 2008 - link
I was just noting how Anandtech's articles are often a little slow to come by (new ones) but WOW! CHock full of great info, insight and indepth information. Its like a good book you just can't quit reading till its done. Great Job GUYS!Christian Packmann - Wednesday, July 2, 2008 - link
1. Are there no CPU drivers for the Phenom? These should allow changing C&Q configuration with Windows' energy options, better than fiddling in the BIOS. This works on my Athlon64 3200+ on WinXP Pro.I'm also running AMD Power Monitor, which allows quickly switching the used energy setting from its tray icons popup menu, so I don't have to open the energy options every time.
This is great for debugging C&Q-related problems, which can happen on single-core CPUs too.
2. I'd guess that the isse with the Phenom is a software bug in the CPU driver or BIOS, but it /might/ be a CPU bug.
CPU frequency changes are always driven in software (doesn't matter if it's a kernel driver or BIOS) by writing to some model-specific CPU registers, see the "BIOS and Kernel Developer's Guide (BKDG) for AMD Family 10h Processors", http://www.amd.com/us-en/assets/content_type/white...">http://www.amd.com/us-en/assets/content...e/white_... .
You can set the VID and Frequency with these registers. A frequency ramp-up or ramp-down usually consists of several steps of changing voltage and frequency until the target frequency is reached. There is a short waiting period after each change until the new voltage step has stabilized.
These waiting periods seem to be contained in some more CPU registers; if these values are wrong, C&Q will obviously not work as planned.
Now I don't know if these waiting values are determined by the CPU or written to it by the BIOS/kernel driver during its respective initialization (I only skimmed this section in the BKDG, not enough time ATM). If they are determined by the CPU itself and C&Q goes wrong, this would indicate a CPU bug. If they are determined by the BIOS however, this would be a BIOS bug and fixable with a BIOS update.
If you find a Phenom motherboard which doesn't exhibit these problems, then the BIOS would obviously be the culprit.
Oh, and a wild-ass-guess: maybe these waiting periods are (in part) influenced by temperature, and vary with changing CPU temperatures - this would of course imply that they aren't determined once at startup, but recomputed at given intervals. This should be testable, too.
3. Even if it's just a BIOS bug, a fix shouldn't completely solve the performance loss with PS, due to the split power planes of the Phenom. As long as the kernel throws threads around the cores willy-nilly, you will get a performance loss if C&Q does work properly. Frequency ramp-up does always take some time if C&Q actually works. This specific problem cannot occur on CPUs with a single power plane (which the C2Qs still have, I think), as all CPUs will always have full voltage as long as a single core runs at 100%; only the frequency might need to be adjusted. Of course the performance loss you measured is extreme and indicates broken C&Q ramp-up speed.
BTW, this wild thread-changing you observed will always cost some performance for most code, as a core change makes the L2 contents useless. This is only 512K for the K10, but on C2Q a change between cores 0/1 and 2/3 will invalidate up to 6MB, depending on CPU model and cache usage. This doesn't matter much with todays memory bandwidths, but I'd still regard this a kernel bug.