Stuck at 4GHz with the Phenom II X4 940...
by Gary Key on January 29, 2009 12:16 PM EST- Posted in
- Gary's First Looks
We have been testing the overclocking capabilities of the Phenom II X4 940 (seriously, who names these products?) for an AMD roundup and have hit the proverbial brick wall. It has not been for the lack of trying or even using a stellar motherboard to test these processors. The motherboard choices have ranged from some wicked little 790GX overclockers from ASRock, Gigabyte, and DFI to the flagship 790FX products from ASUS, MSI, and Foxconn. We even tried a few NVIDIA 780a based motherboards along with a slew of newly arrived AM3 compatible boards. We changed cooling, processors, video cards, disk drives, memory, and tried every available voltage setting. It did not matter. We could not break the 4GHz barrier and still complete our benchmark test suite.
The only commonality between our 30 different setups is the operating system. We recently standardized on Vista Ultimate 64 SP1 for testing. Granted, we had this same problem when our 940 engineering samples first arrived and we asked AMD about it. However, AMD never did get to the bottom of it before the launch date. We thought our results might change with retail processors. Alas, they did not. We have four retail CPUs, three with 0850 lot codes and one from the 0849 batch that all behave the same way under Vista 64.
Our final benchmark stable clock speed is 3.955GHz reached via a 17.5 core multiplier and a 226 HTT setting on our . This required a 1.6V VCore setting (with droop, real voltage is around 1.585V) on our DFI DK 790FXB-M2RSH motherboard. Memory speed is DDR2-1205 at 5-5-5-18 timings with VDimm at 2.060V. This is the setting we will utilize in our upcoming roundups. We mention it now as our Core i7 920 will operate at 4GHz and Q9550 at 4.25GHz, not exactly fair, but we are looking at platform capabilities on air cooling in the overclocked sections. As one would say, it what it is.
What is really strange is the behavior of the OS and Phenom II X4 940 at the 4GHz mark. We actually have 3.990GHz (19x210) stable for all tests except Crysis and the PCMark Vantage TV/Movies test suite. With that in mind, a simple change to 19x211 for a 4.009GHz clock speed results in the majority of our tests failing. We sometimes have trouble even entering Vista at 19x211, while 19x210 is about 97% benchmark stable. We have tried every possible combination (20x200, memory at DDR2-800, 1GHz NB speed, etc.) and even chilled the processor down to 16C and raised processor voltages above 1.7, nothing worked above 4GHz.
At least under Vista 64 as Vista 32 was much different. The settings mentioned earlier allowed us to reach a stable 4.275GHz (19x225) with the same components. However, we are not utilizing Vista 32 in testing anymore, especially considering our standard benchmarks are completed with 4GB and 8GB configurations on the DDR2 platforms. As such, it appears at this time that any overclocking comparisons will be limited to under 4GHz on the AM2+ and AM3 platforms. We have addressed this problem with AMD again and hopefully an answer is forthcoming. In the meantime, we figured out a way to get a screenshot above 4GHz before we received the standard BSOD routine. At least it is a consolation prize at this point.
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helldrell666 - Friday, January 30, 2009 - link
And what else Inteltech...doesn't like about the new AMD processor?I got the processor myself two days ago and it's now clocked at 3.62GHz on stock voltage operating like a champion.
I think that You, Inteltech, should not be allowed to review AMD products.Stick to your Intel cpus and great gpus and leave AMD alone.the same goes for those N-vidia sponsored sites.
Adul - Friday, January 30, 2009 - link
Considering that this site was favorable to AMD for a long time I find it odd you call them bias. Fanboi much.MagnumMan - Friday, January 30, 2009 - link
I am experiencing the same kind of wall, at a lower frequency. I have an 0850DPCW Phenom II X4 940 under water cooling with 4x2gb memory running at DDR2-960, FSB 240, 5-5-5-12-2T @ 2.2V. I have the CPU running at 3.6GHz @ 1.4125V, HT is 2.4GHz @ 1.325V. I have tried pushing the voltage as high as 1.65V on my ASUS M3A79-T Deluxe board (both CPU and NB..) with the reference voltage as high as 2.7V (currently 2.6V) but I cannot get the CPU stable even at 3.66GHz by dropping the FSB and raising the multiplier. I tried for many days to get past 3.6GHz and I cannot. I also have 3x 3870 overvolted and cap-modded, running 965/1250 in 3-way crossfirex and I can play Dead Space until I'm blue in the face at 3.6GHz, or run prime95 for 24 hours. But I go up to just 3.66GHz and prime95 dies in a matter of minutes. Lastly, I am using Vista 64-bit... I do wonder if this is due to the 4x2gb memory... when testing Vista 32-bit were 4 memory sticks used or not? That could be the difference. I expected a lot more out of the CPU... mind you it beats the Phenom 9850 BE which I got to 3GHz on this platform so I'm not complaining much, I expected to get to 4GHz or more.East17 - Friday, January 30, 2009 - link
That's all ... There is need to test the OC capabilities in WinXP 64 Bit & 32 Bit and then in Windows 7 32 Bit & 64 Bit and then we will have the whole picture.Right now there is not much that we can conclude from these tests besides the obvious : "There is something strange here"
Some tests in Win2003 Server R2 with all the workstation features enabled would be also usefull .
ssj4Gogeta - Friday, January 30, 2009 - link
How do I use the formatting toolbar while posting a comment? When I click on bold, italics, or underline, nothing happens. And when I click on the link button, it asks me for url and text, but when I click on OK, nothing happens. Same for Quote button. I have javascript turned on. Please help. :)Calin - Friday, January 30, 2009 - link
bolditalic
underlined
I can't either - but you can manually edit the posts with [ B ] ... [ / B ] and so on
ssj4Gogeta - Friday, January 30, 2009 - link
"We mention it now as our Core i7 920 will operate at 4GHz and Q9550 at 4.25GHz, not exactly fair..."It IS fair. It's not Intel's fault that AMD can't make better overclockers.
duploxxx - Friday, January 30, 2009 - link
again, not in same price range, why don't you take a compare of q82-q8300 then against p2 940 afterall that is what intel is doing lately, schrinking the cachesduploxxx - Friday, January 30, 2009 - link
why do you use a Q9550 in this test against ph2 940, the direct price competitor is Q9400 ......... compare what you need to compare also ddr2 against ddr2. If not there is no added value to this review.Calin - Friday, January 30, 2009 - link
As the 64-bit software exercises more of the internal structure of the processor (extra registers and so on), there might be a local hot spot or maybe some critical path only under 64-bit software.Could you please try with another 64-bit operating system that limit in overclocking? It shouldn't take long to confirm/infirm this using either a version of Linux, FreeBSD, OpenSolaris, and you could test stability with Prime95 (mPrime) or something else. Even a live CD might be of use for a bit of testing
Thank you
P.S. As the scope of the articles grew and grew (compared to the years past), they appear less and less often. These blogs are very nice in keeping the front page lively