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Core flux...

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July 7, 2006 4:17:15 PM

I have an Asus A8R32-MVP with an Opteron 175 running at 2.6GHz using 1.475 volts, PSU is Antec TruePower 550watt... But using Asus PC Probe, my VCore fluctuates from a 24hr low of 1.42, to a high of 1.49 volts... with most fluctuations (90%) staying within 1.44 volts to 1.47 volts...
The other voltages are stable to within ~0.01 volts...

Is this enough to cause an instability (even tho system is very stable)?
Enough to be the reason OC over 2.8GHz is rocky?
What is the weak link causing most of this flux?

More about : core flux

July 7, 2006 4:44:11 PM

**bump**
[/Does it take inq. links to get replies?] :wink:
July 7, 2006 5:11:30 PM

Are you perhaps running Cool and Quiet on the cpu?
That will boost and drop the voltage up and down a good bit.

Edit:

Hmm, you're running that thing OC'd huh?
Maybe the motherboards power supply is a little careless, but still it's not a very big flux, it might change due to how much work it has to do, check if running a benchmark doesnt keep it down a notch.

Why running at that high voltage anyway? Mine will run just fine at 2,4 with 1,3v
Related resources
July 7, 2006 5:18:52 PM

Yes, it can cause instabilities and I have the exact same problem with my ASUS A8N SLI-Premium. I've actually found that some voltage settings fluctuate more than more. It is for that reason I recommend you play around with the voltage to find the more stable values. Failing that, add an extra "tolerance" voltage to add in a factor of safety. I've actually found that raising your voltage from 1.40->1.45 doesn't increase the temperature of the CPU by more than 2'C if you don't increase the frequency.
July 7, 2006 5:30:58 PM

You've got your voltage pretty high it seems for such a minor overclock on an Opteron. I've got an Athlon and I don't have my voltage that high.
July 7, 2006 5:39:40 PM

Quote:
I have an Asus A8R32-MVP with an Opteron 175 running at 2.6GHz using 1.475 volts, PSU is Antec TruePower 550watt... But using Asus PC Probe, my VCore fluctuates from a 24hr low of 1.42, to a high of 1.49 volts... with most fluctuations (90%) staying within 1.44 volts to 1.47 volts...
The other voltages are stable to within ~0.01 volts...

Is this enough to cause an instability (even tho system is very stable)?
Enough to be the reason OC over 2.8GHz is rocky?
What is the weak link causing most of this flux?

I am not sure how precise is the voltage measurement, but if in average you are getting the voltage you have set, than it seems OK.
Anyway, what is the rest of the hardware you have, what is the peak power of your PSU and what tasks does you give to the system, when this voltage fluctuations ocurs?
Also, about the CnQ option from BIOS. Have you tried with it enabbled/disabled if something is different with the voltage?(no matter that you have no Athlon64 driver installed)
July 7, 2006 5:53:27 PM

from my experience and from what ive heard ASUS boards are notorious for voltage fluxuations.

i have a ASUS P5P800-SE and even with no OC @ stock voltage mine fluxuates from 1.35 to about 1.41.

it may just be ASUS
July 7, 2006 5:55:01 PM

Peak voltages is not the key unless heis pushing his PSU to the limit. As you can see from this picture courtesy of Legit reviews, some PSUs are more stable than others.



On top of that some PSUs are incredibly stable 99.99% of the time but every now and then drop massively. It's bloody difficult getting the perfect PSU which is why you just have to add a factor of safety to the voltage settings.
July 7, 2006 5:55:46 PM

These are my sytem specs...
Lian Li PC-60plus Black Aluminum Case (w/TR-3B Black Thermometer/Fan Controller 3.5” bay and a L.I.S.2 (5.5” bay USB LCD Fan Controller))
Opteron 175 (OC’d 2x 2.64 GHz, 2MB cache, Socket 939, .09 micron, E6 stepping, OSA175DAA6CD)
ThermalTake BigWater 745 liquid cooling system complete kit
Asus A8R32-MVP Motherboard (ATI Radeon Xpress 3200 CrossFire, socket 939, SATA2)
HiS X1800XT Graphics Card (625 MHz/700 MHz OC core/1500 Mhz/1600 MHz OC mem, Dual DL-DVI VIVO 512 MB PCIe)
ATI TV Theater 550 PRO Tuner (PCI TV and FM Tuner)
4x 512MB Corsair Micro Xpert DDR RAM (2.5-3-3-8-2T (spd 2-2-2-5-1T) TwinXP 1024-3200XL)
2x 74gig Western Digital Raptor Hard Drives RAID-0 (WD740GD RAID0 150gig Boot Drive)
2x 250gig Western Digital Caviar SE16 Hard Drives (WD2500KS storage and data)
Plextor 716AL Black 16x DVD/CD Burner (IDE slot loading type)
Antec TP-II 550 Power Supply (550 Watt ATX12V v2.0 PSU)
Dell 2405FPW 24-inch LCD Monitor (UltraSharp Wide Aspect Flat Panel Display)
Logitech G-15 Gaming Keyboard
Logitech Cordless Optical TrackMan
Case Fans (PanaFlo 120mm intake, Adda 120mm exhaust blower, PanaFlo 120mm internal circulatory Fan, PanaFlo 92mm exhaust and PanaFlo 80mm Fan)

The voltage flux occurs when browsing net, outlook open, and diskeeper in background...
Granted, it is within spec... but am curious as to the reason for this fluctuation... IE is it the 3phase power on the mobo... the PSU, or what?

Benchmarking hits pretty high according to FutureMark’s results ~ 5,040 3DMarks06 and 10,900 marks in 3DMark05.

also...
Measurements and Analysis of Power Draw consumed from this Opteron PC using "Kill-a-Watt" meter.
Based on a brief quick test, and several follow-ups, I preclude that my AMD Opteron rig when over-clocked at 2420MHz from 2200MHz consumes:
≤ 200 Watts at Idle
≤ 250 Watts during Boot Up
and
≤ 350 Watts at maximum load when benchmarking using 3DMark06 (at 75% efficiency, my PC is requiring ≈ 265 watts of true power from my power supply)
Note: This is only the PC measured at outlet from the Power Supply; my LCD Monitor was not measured per these results.

I have set the voltage to 1.475 volts, because I have concluded that my CPU needs at least 1.4 volts to be stable 24/7 at 2.64GHz which this accomplishes... thus 1.475 does that at a minumum... btw at 1.45 volts, the low drops to 1.38 volts (and occasionally an error will sneak in), which all in all is still within 5% of target voltage requested...
July 7, 2006 6:11:45 PM

your PSU seems to have enough power to be stable, especialy for the mentioned case when browsing and other unrequestfull tasks.
As other discutant mentioned it might be just ASUS. On my A8N5X(moded to A8N-E) the voltage is always 0.05v more than the setting in BIOS, but it is fluxing (+- 0.0125) very rare and for a short moments, and than again it is 0.05v higher than the setting in BIOS. Strange
July 7, 2006 6:44:08 PM

RichPLS I'd say you're more of an expert than most of us here, but using eXtreme OuterVision's PSU Calculator and the specs you provided, I came up with the need for a 535W PSU needed. I substituted 10,000 RPM SCSIs for your Raptors and Thermaltake's CL-W0005 BigWater for your BigWater 745 (not certain if I was right in doing that). I also spec'd hi-performance fans just in case and spec'd the CPU OC at 2.7 @ 1.475 V. All in all, I think I might have done a bit of overkill when setting the parameters of the calculator, but even when I skimped it was still around 507W needed.

It seems like you could be straining the PSU too much when you try to get past 2.8 because setting the CPU OC on the Calc to 2.8 at 1.49 pushes the requirements to 545W. Possibly even a combination of both the PSU and motherboard voltage regulators being stressed at those speeds. I believe DFI uses 4 Phase regulators on their boards but justifying the cost of a new PSU and board might be difficult right now, especially with Conroe around the corner.

I guess you could buy a new PSU and motherboard, but you've already got a very nice setup. It's up to you to justify the cost of spending more money on it.
July 7, 2006 7:03:57 PM

My system is not using hardly any power, it's about as barebones as you can get and my voltage fluctuates as much as yours. My power supply is far more than enough, but I also have a 3 phase MB. Most 3 phase boards I've seen fluctuate this much. The only people I know who don't have a bit of fluctuating are using 4 phase (or more) boards along with the adjustable rail OCZ power supplies. Even then, you'll likely to see a fluctuation of .02 volts or so depending on load.
July 7, 2006 7:08:23 PM

Quote:
RichPLS I'd say you're more of an expert than most of us here, but using eXtreme OuterVision's PSU Calculator and the specs you provided, I came up with the need for a 535W PSU needed. I substituted 10,000 RPM SCSIs for your Raptors and Thermaltake's CL-W0005 BigWater for your BigWater 745 (not certain if I was right in doing that). I also spec'd hi-performance fans just in case and spec'd the CPU OC at 2.7 @ 1.475 V. All in all, I think I might have done a bit of overkill when setting the parameters of the calculator, but even when I skimped it was still around 507W needed.

It seems like you could be straining the PSU too much when you try to get past 2.8 because setting the CPU OC on the Calc to 2.8 at 1.49 pushes the requirements to 545W. Possibly even a combination of both the PSU and motherboard voltage regulators being stressed at those speeds. I believe DFI uses 4 Phase regulators on their boards but justifying the cost of a new PSU and board might be difficult right now, especially with Conroe around the corner.

I guess you could buy a new PSU and motherboard, but you've already got a very nice setup. It's up to you to justify the cost of spending more money on it.


Thanks for some excellent feedback... and I agree it could be the PSU is being strained when I try for 2.8 or higher... I don't think it bugs me enough to invest in a new PSU and mobo just for this rig, but I will opt for just that on next build... just wanted to have some diverse input on this particular build as to some possible reasons...
July 7, 2006 7:17:26 PM

Here is what I have found with my Opty 165. With CNC off, and with it overclocked to 2.9ghz, if I set the voltage to 1.4 in bios, cpuz reports 1.375-1.392 fluctuactions..... at that setting it will fail prime after many hours. I bumped the voltage up to 1.425 and now it stays solid @ 1.392 and does not fail prime or anything else for that matter. That small flux could be the difference between being stable and not stable. It used to fail prime around 10-12 hours, now I can run prime as long as I would like, play games, and do anything else I choose to do with no problems simultaneously.

System specs....
2 74g Raptors in 0
2 250g Segates 0
Opty 165 @ 2.9
2 7800gtx's OC'ed
Antec Neo Power 480
and all the other normal stuff which I dont really care to mention.

I did have 6 hard drives in it before but I removed 2 because of heat issues in the HD cage....

That PSU should be able to handle what you have with no problems. My max draw has been around 330 under Prime, a 3d stress test, and read/write ops..... at boot it would not even get that high if I remember correctly.... and I also tested it with a kill-a-watt.
July 7, 2006 7:26:20 PM

Yes, I have Cool and Quiet disabled in the BIOS...

also, repeating... it seems by my investigations, that my CPU on this configuration, needs a minimum of 1.40 volts for stablity, and to achieve this, I have to set BIOS voltage for VCore to 1.375 volts plus 0.10 overvolting boost, which keeps my voltages in the range of 1.44 to 1.475, with occasional fluctuations to a low of 1.41 and highs to 1.49...
July 7, 2006 7:43:35 PM

does it not work if you just set the vcore to 1.475?
July 7, 2006 7:45:04 PM

weskurtz81, what motherboard are you using with that setup?
July 7, 2006 7:53:00 PM

I have the expert currently, I was using an Asus A8N SLI Premium before though, and I did notice fluctuations on it as well, the reason I switched was because the FSB maxed on the ASUS board at around 310.
July 7, 2006 7:57:36 PM

Quote:
I have an Asus A8R32-MVP with an Opteron 175 running at 2.6GHz using 1.475 volts, PSU is Antec TruePower 550watt... But using Asus PC Probe, my VCore fluctuates from a 24hr low of 1.42, to a high of 1.49 volts... with most fluctuations (90%) staying within 1.44 volts to 1.47 volts...
The other voltages are stable to within ~0.01 volts...

Is this enough to cause an instability (even tho system is very stable)?
Enough to be the reason OC over 2.8GHz is rocky?
What is the weak link causing most of this flux?


Id say thats pretty normal.. if you tink yours is bad.. this a8nsli only gives 1.5v in bios, but in windows it gives 1.55, and it will flux from 1.49-1.61.. pretty neat eh :lol: 
July 7, 2006 8:08:48 PM

Blame Asus for that.
I for instance, had to update my bios to the latest official version (1009) just to get the cpu voltages corrected. I couldnt set at 1.45. Just 1.4 or 1.5 and up! all those missing options were enabled after a flashing.
July 7, 2006 8:18:38 PM

1.45volts is the highest without using Asus Overvolting BIOS utility... and max overvolting is 0.20 volts, making max voltage to the AMD dual-core Cpu being 1.65volts... which actually on my rig gives you a flux range of 1.55 to 1.67volts :? Which BTW, does not enable me over 2.8GHz stabily
July 7, 2006 8:19:39 PM

Quote:
1.45volts is the highest without using Asus Overvolting BIOS utility... and max overvolting is 0.20 volts, making max voltage to the AMD dual-core Cpu being 1.65volts... which actually on my rig gives you a flux range of 1.55 to 1.67volts :? Which BTW, does not enable me over 2.8GHz stabily


Sounds like you need an abit ;) 
July 7, 2006 8:28:29 PM

Quote:
I have the expert currently, I was using an Asus A8N SLI Premium before though, and I did notice fluctuations on it as well, the reason I switched was because the FSB maxed on the ASUS board at around 310.

I suspected DFI (again 4 Phase regulators). You also have a higher quality (No offense RichPLS) PSU, even though its a lower power unit. Putting those in the equation could have a lot to do with your high overclock compared to RichPLS's.

Abit used to make the best overclocking boards. However ever since "Wu know who" went from Abit to DFI, DFI seems to have the best overclocking boards currently (for 939).
July 7, 2006 8:29:31 PM

YEs, maybe... but that was not an option when I purchased Asus... and all in all, this board kicks A$$... and is running 4x512MB DDR RAM chips...
besides...
Point of this post was not to find better hardware, but to answer questions of the reason(s) for the voltage fluctuations measured...
July 7, 2006 8:33:16 PM

From my OC experience on about 6 different K8 cpu's, once the voltage increases start, I would only get about 2-300 mhz more out of them. Like this one I am using now, I can get it to 2.9ghz on stock voltage according to AMD (1.35-1.4) and it runs @ 1.392..... but it tops out @ 3.1-3.2 ghz.... all the others have been about the same, they would go up to about 2.4-2.5 stock and then 2.65-2.7 would be max. However, only once have I used more than 1.55vcore to achieve max OC and I was using watercooling for obvious reasons. The watercooling did help make it stable @ 2.8 using over 1.6vcore but imo it was not worth the trouble for the extra 100mhz. It was an AMD 3000 btw. I am sure you knew most/all of that, just thought I would type it. I have tried a number of different boards as well, 2 premiums, 2 A8N5X's, 3 DFI's 1 Expert 1 SLI DR and 1 Ultra D..... The Ultra D could achieve a 400mhz FSB, the SLI Dr did not go much above 320, and the expert is N'A, I have not tried to find the max FSB of it because I have not needed to. The Premium went up to about 310 or so, and the 5X went up to 333..... for overclocking I would still choose lanparty, and even went back to DFI after the Premium, the only reason is because of the more "garunteed" FSB OC'ing.... I know it never is but with this board I felt like I had a better shot. I really liked the Asus boards though, just not quite on par with the expert I currently own, as far as OC'ing is concerned. But, IMHO, they are above the DFI boards on EVERYTHING else.
July 7, 2006 8:51:32 PM

Quote:
You've got your voltage pretty high it seems for such a minor overclock on an Opteron. I've got an Athlon and I don't have my voltage that high.


It is'nt that high, I need to feed mine with a lot more voltage (43rd week of '05)

I regret not waiting a bit longer for a '06 Manchester...
July 7, 2006 8:51:44 PM

From what I have read, the cpuz reports and such are an analog signal converted to digital. I know in some digital systems on aircraft, they tend to do something we refer to as hunting. Autopilot for instance tries to keep the surfaces at the 0 position, and while on the ground with no pressure on the surface the control columns tend to oscillate. From the way I under stand it digital systems are so precise that you will get these fluctuations like most of us see. Your cpu might be requesting vcore 1.400 and then it might bump it up just a hair. When it converts that analog signal into digital it may not be giving you the exact measurement, and it also might be hunting a little. So, in other words, it might not be bouncing around quite as much as it looks like. Am I going in circles here? Also, what stepping is your cpu? I have not read much about 170's or 175's going much above 2.7.... atleast that was the case with the older ones.
July 7, 2006 8:58:23 PM

I remember I brought this up with my P4 northy. I'm on an old Asus board, and I had to increase the voltage to get what was considered a stable over clock on Prime95.

I know when my P4 would sit at idle, it would jump around 1.63 to 1.83.

Under a full load it would sit more on 1.68 (in the bios was set for 1.675). I didn't like it jumping past 1.70 volts.

I guess my question would be, would it show a more stable vcore reading when the opty is under full load?
July 7, 2006 9:02:09 PM

mine doesn't move at all.... idle or load, unless of course I have CNC enabled.
I have seen one of my other cpu's flux on one core moreso than the other though.
July 7, 2006 9:28:00 PM

Quote:
I have an Asus A8R32-MVP with an Opteron 175 running at 2.6GHz using 1.475 volts, PSU is Antec TruePower 550watt... But using Asus PC Probe, my VCore fluctuates from a 24hr low of 1.42, to a high of 1.49 volts... with most fluctuations (90%) staying within 1.44 volts to 1.47 volts...
The other voltages are stable to within ~0.01 volts...

Is this enough to cause an instability (even tho system is very stable)?
Enough to be the reason OC over 2.8GHz is rocky?
What is the weak link causing most of this flux?



I believe that's Cool&Quiet. because it throttles parts of the CPU, it will fluctuate. Also, with analog regulators, this is a factor. I notced that with my 4400+. it fluctuates between 1.35 and 1.39 or so. Also dirty power can cause voltage spikes.

I'd say it was a combination of all of the above.
July 7, 2006 9:47:47 PM

I personally dont think that those wattage calculators are very accurate. They say that my computer uses more than 400 watts of power at full load and I've never recorded the usage over 250 watts. The dell psu that was shipped with it is 310 watts and i've never had crashing from too little power, which would usually happen when I'm overclocking the vga and running stress tests on everything at the same time, which I've done tons of times. If those things are correct, then most of the world has an underpowered computers.
July 7, 2006 10:07:20 PM

Quote:
It is'nt that high, I need to feed mine with a lot more voltage (43rd week of '05)

I regret not waiting a bit longer for a '06 Manchester...
Opterons usually run at a lower voltage, so a large voltage increase shouldn't be required for such a small overclock.
July 7, 2006 10:29:13 PM

As I hinted at in my previous post, the datecode plays a big role in how much of an overclock one can get using stock Vcore, there is a noticeable difference between late '05 and early '06 cores.
July 7, 2006 10:41:29 PM

Quote:
**bump**
[/Does it take inq. links to get replies?] :wink:


I tried searching the inquirer but couldn't come up with anything. :cry:  :tongue:
July 8, 2006 12:26:40 AM

Quote:
I have an Asus A8R32-MVP with an Opteron 175 running at 2.6GHz using 1.475 volts, PSU is Antec TruePower 550watt... But using Asus PC Probe, my VCore fluctuates from a 24hr low of 1.42, to a high of 1.49 volts... with most fluctuations (90%) staying within 1.44 volts to 1.47 volts...
The other voltages are stable to within ~0.01 volts...

Is this enough to cause an instability (even tho system is very stable)?
Enough to be the reason OC over 2.8GHz is rocky?
What is the weak link causing most of this flux?



I believe that's Cool&Quiet. because it throttles parts of the CPU, it will fluctuate. Also, with analog regulators, this is a factor. I notced that with my 4400+. it fluctuates between 1.35 and 1.39 or so. Also dirty power can cause voltage spikes.

I'd say it was a combination of all of the above.

Baron, Sorry for not stating in first post that Cool and Quiet has always been disabled on my mobo from the BIOS...
I stated this in a previous post within this thread...
July 8, 2006 12:31:41 AM

I have a Toledo Core, E6 stepping...
July 8, 2006 12:33:33 AM

Quote:
**bump**
[/Does it take inq. links to get replies?] :wink:


I tried searching the inquirer but couldn't come up with anything. :cry:  :tongue:

[/kicks dirt] Thanks... :roll:
July 8, 2006 12:43:02 AM

As I say I've seen fluctuation in my 4400+. I'm looking at CPUz now and it does fluctuate but not more than .07 volts. I would say that I may be able to cut it down if I get a Monster power strip. It does wonders for my Onkyo 5.1.


Try that. Also try better a better plug for the PS.
July 8, 2006 12:51:53 AM

I am using 3 UPS's... a 1500 one, a 1100 APC one, and a 500 APC...
One for monitor, one for PC, other for peripherals...
July 8, 2006 2:56:48 AM

Quote:
I am using 3 UPS's... a 1500 one, a 1100 APC one, and a 500 APC...
One for monitor, one for PC, other for peripherals...



I guess by process of elimination, it is a factor of analog regulators in a digital environment. Since CPUs are digital. I have C&Q on.
July 8, 2006 6:31:31 AM

aye, matey... but read the post... I have CnQ disabled, since I am overclocking this CPU by 440-MHz... but have stability issues when approaching or surpassing a 600-MHz overclock...
Hence the post, which was to gain insite as to whether it was the PSU rail fluxing or the VRM on the mobo's 3 phase supply causing the fluctuations...
I suspect the mobo's VRM as the culprit, just not 100% sure... :?
July 8, 2006 6:49:42 AM

yep, blame asus mang.
July 8, 2006 9:13:04 AM

Quote:
:cry: 

don't cry for me Australia. 9-nm will find very "interesting" "articles" from the_inq. He has the power of selection and the power of making threads.
July 8, 2006 4:47:45 PM

Quote:
aye, matey... but read the post... I have CnQ disabled, since I am overclocking this CPU by 440-MHz... but have stability issues when approaching or surpassing a 600-MHz overclock...
Hence the post, which was to gain insite as to whether it was the PSU rail fluxing or the VRM on the mobo's 3 phase supply causing the fluctuations...
I suspect the mobo's VRM as the culprit, just not 100% sure... :?


Rich.. I'm not quite sure, but did you say you have CnQ disabled? :p  ..

I don't trust Antec PSU anymore... I've seen some that blowed they capacitors or just quit working.. Antec is no more on my PSU list of choice..

But.. as you said that the system is very stable and did not give you any problem before, then I guess that you are just trying to find some reason to justify an upgrade to a Conroe.... :wink:
July 8, 2006 7:18:54 PM

:lol:  Not really, I love my rig, and it performs like a champ...
I just wanted to answer some lingering questions on some irregularities it seems to possess... I mean, I am able and do run stable during 24/7 operation at 2.64GHz, using an average voltage of 1.45 vcore... and temp is at 41C...

My sys performs 5,040 3DMarks06 and 10,900 3DMarks05...

Antec is still a stable and strong manu of PSU's regarding thier TruePower series... imo...
July 10, 2006 5:36:10 PM

I dishonor dirt...I only afford SmartPower. :(  [/AsianAccent]
!