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
More Problems?
The Phenom’s flaky Cool'n'Quiet performance in some of our benchmarks forced us to test with it disabled, unfortunately with it disabled we ran into another problem: stability.
Gary originally wrote about this in his Postcards from the Edge blog. Many mainstream motherboards ship with low cost 3-phase power delivery circuitry, which is unfortunately insufficient to handle the current draw of AMD’s very high end 125W and 140W TDP processors. Despite the problems Gary initially encountered with many early boards (both AMD and Intel platforms), many manufacturers continue to certify 125W processors like the Phenom X4 9850 BE on their mainstream boards.
While it’s unlikely that a user would drop a 9850 into a 780G motherboard, it is possible that someone would take a Phenom X4 9550 and attempt to overclock it too far on a 780G - resulting in the same problems.
With Cool'n'Quiet enabled, our power load on our testbed Gigabyte 780G was just fine - the motherboard had no problems uneventfully completing our entire test suite. However, with CnQ disabled as we had to do in order to get the best performance results out of Phenom our 780G board was noticeably less stable. While it completed most tests without issue, we couldn't complete a run of Windows Media Encoder 9 without cooling the power delivery circuitry on the motherboard. A simple case fan did the trick:
The Cool'n'Quiet issues we encountered clearly have much further reaching implications than erratic performance in a few benchmarks.
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Sylvanas - Tuesday, July 1, 2008 - link
Wheres the 9950BE overclocking results? It is an unlocked CPU so what about Overclocking the NB? What performance difference does that bring? I doubt people that buy IGP's are going to overclocking much anyway since they are usually silent HTPC rigs...Gary Key - Tuesday, July 1, 2008 - link
The 9950BE overclocking results are coming in a different article. Unfortunately, our 790FX boards (they have been beat on for six months) were not exactly up to speed and we thought it would be better to not show anything instead of a 2.8GHz clock that obviously is not representative of the processor at this point.Also, most of our previous results were run on the 780G, a chipset that when tuned correctly and on a good board will outclock the 790FX with a discreet graphics card by the way. Jetway just released a fairly comprehensive BIOS for their new 780G we ended up using after the others started failing. We just received BIOS updates for the 780a boards and have a new 790FX/SB750 arriving shortly for a CF/SLI update on AMD (gaming is not that bad by the way on the Phenom for the mid-range market).
Increasing the NB core (IMC) clock (in Phenom it runs async from the Core Speed unlike Athlon which is Sync) drops latencies (especially L3) and increases memory performance/throughput, which in turn improves system performance. The Phenom starts to come to life when you hit a 2.6GHz core speed with a NB core clock at 2200MHz+. Depending on the application and CPU, increasing NB core speeds (getting up to 2200MHz+) can result in performance differences from 3%~12% in most cases.
Almost as important is increasing HT speed for further optimizing the pipeline links (CPU/Memory/PCIe,etc). Our 9950BE follow up will have an overclocking guide along with optimization details.
Sylvanas - Wednesday, July 2, 2008 - link
Excellent, thanks for the info Gary- I look forward to the follow up 9950BE overclocking article. If there is some info on the SB750 aswell that's even better :)DigitalFreak - Tuesday, July 1, 2008 - link
AMD post X2 = ROFLMAOThe C&Q thing is probably another respin waiting to happen. What a bunch of boobs.
acejj26 - Tuesday, July 1, 2008 - link
what's a seccond?why didn't you include the 9950 in the first page of benchmarks?
is the 9960 a new processor from AMD?
i've come to expect these errors from other staff writers, but not you Anand.
skiboysteve - Tuesday, July 1, 2008 - link
why are you using 780G to overclock and check stability on the same article you say how someone else wrote an article about how that is a bad idea because of power...you even say at the bottom of your overclocking page, a mere footnote, that you got higher clocks on a different platform
js01 - Tuesday, July 1, 2008 - link
I think they scale much better then that hothardware got the 9950be to 3.1ghz barely even trying and the 9350e to 2.7ghz.http://www.hothardware.com/Articles/AMD_Phenom_X4_...">http://www.hothardware.com/Articles/AMD...nom_X4_9...
Gary Key - Tuesday, July 1, 2008 - link
It depends on the board and CPU actually. We have a retail 9850BE that will do 3.3, but three others struggle to make it to 2.8. Until we see some consistency in the retail parts, we would rather play it safe with the comments. A separate overclocking article is on its way though with the new lineup. :)woofermazing - Tuesday, July 1, 2008 - link
Odd that you guys couldn't get any OC out of the 9950. Results from other sites have been pretty impressive using the stock cooler. 3.6ghz is the highest of seen so far.Clauzii - Wednesday, July 2, 2008 - link
I second that!PS: And why does the comment page keep looking like pre-95 internet :O (I'm on FF3)