Core flux...

[RichPLS]

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?

 

[RichPLS]

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

 

[asdasd123123]

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

 

[Kholonar]

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.

 

[Heyyou27]

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.

 

[gOJDO]

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)

 

[HYST3R]

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

 

[Kholonar]

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.

 

[RichPLS]

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...

 

[gOJDO]

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

 

[Anoobis]

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.

 

[shabodah]

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.

 

[RichPLS]

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...

 

[weskurtz81]

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.

 

[RichPLS]

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...

 

[weskurtz81]

does it not work if you just set the vcore to 1.475?

 

[Anoobis]

weskurtz81, what motherboard are you using with that setup?

 

[weskurtz81]

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.

 

[freeagent]

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:

 

[NEO3]

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.

 

[RichPLS]

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

 

[freeagent]

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

 

[Anoobis]

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).

 

[RichPLS]

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...

 

[weskurtz81]

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.