Help Overclocking & Rounding Errors

[xguntherc]

OK, so I need a little help here. I know the basics to overclocking. but I'm having problems.

I have a Q6700 Quad Core 2.66

Right now I'm at 3.5 GHz with good temps of 38C Idle.

So Here's my problem. I Run Prime 95 to make sure my system is stable. but either something is wrong. or that program is not stable itself.

My Computer is completely stable and passes Hours of Prime at 3.1 GHz and at 3.33 GHz yet for some reason no matter what I do. it Fails within minutes on 3.2 GHz. Then it's completely stable and passes at 3.4 but it fails within minutes at 3.5, 3.55 and at 3.6 and at 3.6 two of the cores fail instead of one.. I get the Same Error everytime it does happen to fail. It's the Rounding Error. It says Error Rounding was 0.5 when expected less than 0.4 I don't know what that means. or how to stop this from happening. So if anyone could please help me figure this out I'd really appreciate it. and ya ya why not stay at 3.4 GHz. well I will probably use that for my 24/7 speed. but I want to have the option to be stable at 3.6 or so for Benchmarks and what not.. at 3.6 I can play games perfectly fine, benchmark and what not. but I can't pass Prime95..

Idea's are very much wanted..

Thanks!

 

[Fumz]

I'm not sure I'd call your situation a "problem". 3.4GHz quad guys go to the back of the problem line.

If you just want to pass prime at 3.6 then I'd say your only "problem" is most likely insufficient vcore.

 

[johngalt]

Might be a voltage issue - since we have the same mobo basically, I have a weird one - at my 3.375 speeds I get BSODs whenever I come out of sleep - but i I bump it down to 3.21 (1428 FSB) the machine works flawlessly.

I have all the voltages in the green, but maxed to the green, except my RAM - it s rated at 2.1 but I am running at 1000 and 2.0 without any problems. I next plan on bumping the RAM from 1000 to 1066 since that is what it is rated at , but I haven't had time for the tests...at least not until I get an OS that boots a lot faster / has a lot less running....

lmfao - Fumz, not only were we typing at the same time, we were thinking the same thing....

 

[xguntherc]

lol ya ya I know. It's not much of a PROBLEM.. more as me just being picky.

and if your all in Green still then I'm higher than you.. I was at stock clocks all the way to 3.1 also. but at 3.2 and above I changed them. right now at 3.5 Ghz I have volts set to 1.40 and I heard thats pretty high as some hit 3.8 or higher at that voltage on Q6700.. and I know I have a good chip because the VID.. so I'm not really sure. I could try going to 1.45 but I don't wanna go to much higher than that. even tho temps are still great. at 3.625 my temps were idle around 40C even that was stable in all ways but Prime.. so I'm pretty stumped. as everyone will ask. are you Prime stable. so technically I'm not. but I'm at 3.5 right now. and I've been at 3.5 for a good 5 days and not one problem, not one freeze or crash or anything. but for some reason wont pass Prime. very irritating.. but hardly a "Problem"

lol sorry

 

[Fumz]

It doesn't really matter that your idle temps are in the 40's, what matters is your load temps, which will increase exponentially as vcore is increase. I'd stick to 1.4v and under.

My guess is that your "problem" (lol, i still have a hard time with that one) is related to the strap dividers. The gist of it is that there's a sweet spot near each strap and as you move away from one towards the next, performance decreases, then increases again as you get near the next sweet spot. This explains why you fail at 3.2GHz, but are smooth at 3.4GHz.

You may never pass Prime at 3.6GHz without adding so much vcore that it's just not worth it? But again... to the back of the line with you!

 

[johngalt]

I am beginning to realize I might have a weird / faulty CPU. Currently, I have a lot running and I have the following temps:

47-48
49-50
39-40
42-43

That Core2 is really acting strange. There is really no reason it should be that far off the mark.

So, that means I either have a bad contact problem from heatsink to CPU or else I have a faulty CPU....

Hmmm - or else a faulty sensor in CoreTemp - I fired up the nVidia System monitor and it shows

49-50
50-51
42-43
44-45

So is it no that far out. Interestingly enough, after firing up the nVidia System monitor CoreTemp shows a 4-5 degree increase in that Core2 also. It is still lagging behind cores 0 and 1 but is almost acting like it is trying to stay in line with Core3 now....

Here are all the voltages and specs and temps:

 

[xguntherc]

not sure, my brothers machine I built does the same thing as yours.. I've seen people with a core always 6 below and they said it's fine. So I'm not sure about that.

and Fumz, it's not that I "Just" wanna pass prime, it's the fact that like right now I'm at 3.66 GHz and everything works fine, I can play games. I tried Crysis and GRID, I can do benchmarks. and everything is fine, no freezing. nothing. yet I can't pass prime. This speed is completely stable in "MY" eyes. but it fails Prime within seconds. thats where I'm confused. and my Load temp with 2 Primes running is 62-64C so pretty close to my personal limit of 65C and below is ok. So everything is fine, Volts are fine. but Prime is hating me. so I just wanna know if this is ok to run, or if I need to be somewhere that Prime is ok with. thats all.

and as for the dividers.. thats the one area I'm not to familiar with. I don't know much. other than that at 10x Multi thats stock my divider was like 7:9 at 3.4 GHz but now that I'm at a 9x400 Multi my divider is 1:1

so not sure what the deal is. or how I can get it stable.. I know I'm a back of the line problem. but I just wanna get a Mid decent speed to pass Prime. and I will be more than happy. like 3.5 or 3.55 or 3.6 LOL

 

[johngalt]

here's the thing - I turned off that nVidia System monitor, and now coretemp is showing the following:



I personally think it has a hand in why my system goes goofunky at 3.375 - as you can see from the previous posts you know what my voltages are....

Perhaps I am over-volting *too* far with my setup when trying to crank up the FSB?

 

[xguntherc]

well i hate to break this to you.. but you have one of the worse made Q6600's. according to Information gathered and statistics.

HM. lets put it this way. in core temp, that bottom thing. says VID of 1.325
Thats bad, that basically means to get your CPU to run at it's default speed of 2.44 it needs 1.325 v to achieve that. other Q6600's VID are 1.2875, or 1.250 and such. that makes a big difference. as the more you OC the higher it goes. so yours is that high at default. witch means you will reach unsafe "Long Term" volts like 1.55 much sooner than the average Overclocker.. so to be honest with you. I'd not go any higher than 3.1 or 3.2 GHz on that. keep it to 1.4 or 1.45 at the most. some people have reported having a VID of 1.225 and thats great.. those are 4 GHz clockers easy. My Q6700 has a VID of 1.2875 and mine about slightly better than average john. the average people's are around 1.290 or above. my brothers is a 1.265 and I wanna steal it. I might one day.. hehe He'd never know. but some people are lucky and have lower.. Look up "Q6600 VID" in google and you will find threads about it. and people posting Charts with the CPU VID and it's stable oc LIMIT..

your VID is one of the highest I've seen.. Sorry to tell ya. These days people have been buying there CPU's based on batch number and VID number. so if you ever get one used they look for that.. will you do me a favor and take a screenshot of CPU-Z main screen with that high a OC.. and post that for me.

Oh and I've also now been getting my CPU to be completely stable at 3.4 GHz with a 9x Multi instead of 10x. with a 10x multi my divider was like 7:9 and with a 9x multi it's 1:1 and that means it's workin perfectly in sync. thats why I'm passing.. So question Fumz, how do I get it to do this at 3.6 lol

I've been running prime for the last 40 minutes with no problems.. and I'll let it continue for at least 2 more hours hoping for the best.

 

[Fumz]

... and Fumz, it's not that I "Just" wanna pass prime, it's the fact that like right now I'm at 3.66 GHz and everything works fine, I can play games. I tried Crysis and GRID, I can do benchmarks. and everything is fine, no freezing. nothing. yet I can't pass prime. This speed is completely stable in "MY" eyes. but it fails Prime within seconds. thats where I'm confused. and my Load temp with 2 Primes running is 62-64C so pretty close to my personal limit of 65C and below is ok. So everything is fine, Volts are fine. but Prime is hating me. so I just wanna know if this is ok to run, or if I need to be somewhere that Prime is ok with. thats all.

You won't be able to enter the machine in any OC database unless you're 8 hours Prime stable, true; however, how important is that? I think you've already answered your own question? I like to be Prime stable too, but if there's one thing I find more important than being Prime stable, it's game stable. As long as I can do everything and anything I want to with the machine, then I consider it stable. At that point I stop tweaking it and start enjoying it.

I understand completely wanting to get over that last hurdle... it's now a matter of principle... Have you read this yet? Lots of good stuff to help you get over that last little bump: Howto: Overclock C2q (quads) And C2d (duals) - A Guide V1.7 - OverclockersClub Forums

with a 10x multi my divider was like 7:9 and with a 9x multi it's 1:1 and that means it's workin perfectly in sync. thats why I'm passing.. So question Fumz, how do I get it to do this at 3.6

Being in sync doesn't mean anything anymore. In sync, out of sync, what ever gets you the highest clocks is what counts.

 

[Fumz]

I am beginning to realize I might have a weird / faulty CPU. Currently, I have a lot running and I have the following temps:

47-48
49-50
39-40
42-43

That Core2 is really acting strange. There is really no reason it should be that far off the mark.

So, that means I either have a bad contact problem from heatsink to CPU or else I have a faulty CPU....

Hmmm - or else a faulty sensor in CoreTemp - I fired up the nVidia System monitor and it shows

49-50
50-51
42-43
44-45

So is it no that far out. Interestingly enough, after firing up the nVidia System monitor CoreTemp shows a 4-5 degree increase in that Core2 also. It is still lagging behind cores 0 and 1 but is almost acting like it is trying to stay in line with Core3 now....

Here are all the voltages and specs and temps:

View attachment 5416

Nah, nothing weird about what we see here... just that each core doesn't have the same load... which I see you posted below.

The only thing I would do would be to see if you could back off vcore a bit. 1.5 volts is quite a lot. Is this a voltage you arrived at through testing or one you "picked" as a happy medium/starting point?

 

[johngalt]

@gunther - I saw references to VID but never really found a definitive guide / layman's term answer regarding what it was and such - thanks for pointing that out. I am going to buy another CPU, probably a Q9450 anyway, within a couple of months, so I am not too worried - I'd love to be able too show off the fact that I had a 4 GHz OC on air alone, but hey, C'est la vie.

I did not know, either, that there were VID numbers on the CPU (I bought it brand new boxed - should have known I'd get a crappy one for not doing the complete research on the CPU I was getting). Oh well,

Here is the screen shot you requested - using the exact same settings as you saw in my previous two screen shots:



@Fumz - well it is a bit unusual, as Coretemp always reports Core2 as being that much lower than, say Core3 or Core 1 - but then when I took into account the design of the quad core CPUs, I understand more - some of the heat in Core0 has to be overflow from Core1, which is being used a *lot* - and Core 3 is lower than Core0 even though usage is very close because of that overflow.

 

[xguntherc]

see where it says Core Voltage.. your running 1.448 on 3.2 GHz.

I'm running 1.41 on 3.6 GHz and thats because my VID is 1.2875 and yours is 1.3XXX so your CPU starts at that voltage and goes up from there, mine starts under 1.3 and goes from there.. thats what the VID means. and thats how it works. so the lower the VID, the lower Volts the Chip needs to run at stock speeds. so the more room for OC'n.. make sense.. it does to me.

and ya Fumz, you make a good point. as long as everything runs ok like games than screw Prime.. Game stable is a better thing than anything.. although I had someone else say no to that becuase games don't stress your CPU as much as prime.. so I don't know. You're link seems to be a really good read. I'll finish it in the morning. today my PC crashed at 3.7 GHz after about 1 hour and 20 mins. so now I'm chillin at 3.4 where it's Prime stable.. lol whatever that means. Hopefully I figure out more tomorrow on how to get to a stable higher clock. as that guide has some good info on the divider. and I might understand what I need to do now.

Thanks!

 

[Fumz]

Yes, games don't stress the cores like Prime does, but they do stress the overall machine more. If you really want to give the cpu a workout, more stressful than Prime, have a shot at running Linpack: Intel® Math Kernel Library 10.0 - LINPACK - Intel® Software Network

The way to adjust vcore isn't through CPU VID, but through CPU Special VID. Special CPU VID is based on a percentage of CPU VID that allows for small adjustments in vcore while still allowing voltages to lower with the frequency when the machine is idle.

If you set the CPU VID to, for example, 1.35 volts, then it's going to stay at 1.35 volts whether it idles or not. That's not good, especially considering how well the Intel chipsets handle this. This may or may not apply to nVidia boards; not sure how well they throttle?

Always leave CPU VID on auto and make your adjustments through Special CPU VID. You may very well end up with the same amount of vcore, but this way it's able to adjust.

 

[johngalt]

I don't see a Special VID at all on the CPU side - I had originally bumped this up to 1.45 (the last green setting in the BIOS) to test the stability of the 3.375 OC, but other than the wake from sleep BSOD I always get at that speed, everything else seems fine.

I am very new to OCing so I know some of my settings are not near optimal - but this is how I learn things I do, I get advice, I redo, I get more advice, etc.

 

[Fumz]

I haven't run or overclocked anything but DFI boards for years for personal use; they're always loaded with options and Special CPU VID has always been one of them, even on nForce chipsets... but, not every board is a DFI.

Curious, I took a look and indeed you don't have that option. I was actually surprised to see how few options you do have. [H] Enthusiast - EVGA nForce 780i SLI

Without having gotten too deep into your bios, I've got to imagine there's some way to allow vcore to throttle down with the frequency as the machine idles? I'll dig into it later, but for now, that's just my gut feeling as it's a pretty nice board?

@ xguntherc,

Did some reading and found that quads have some difficulty passing more than 4 hours prime on 680i chipsets with anything much above defaults. Have not yet found anything definative on the 780i's, but perhaps the same thing holds true. Apparently passing requires either a lot more vcore than you're giving it, or upping VTT... both are not recommened.

I'll look into this later too to see if I can find anything more definative, but like I said, game stable > prime stable.

 

[xguntherc]

Well the VID from what I understand is a way to tell what the Chip runs at stock speeds.. and ya they throttle down fine. when it does the CPUvolts drops with it. My settings are like that. The CPU Voltage in My Bios is set to Auto. and I think the auto us at 1.40V and then I moved up the FSB volts to 1.40 to go along with my OC since stock was 1.2875 and that my fsb is uped to like 1500 give or take. So the only Voltage I've actually adjusted from the default setting is my RAM. I went to 2.1v like the box recommends to achieve the 5-5-5-15 timings. but now that I'm at 1:1 they auto's to 5-5-5-14. then like I said, my Core Voltage is set to Auto, and I've pushed the FSB to 1.40

I don't know if I need to actually manually change my Core Volts. or if I need to add more to the NB or anything. but for now I'm ok at 3.4 I guess. I don't "NEED" anything higher, I just wanted to get higher for Benchmarks and such. thats all. but for 24/7 I'm probably just giong to stick with this.

Oh and I don't actually have the 780i like he does. I have the eVGA 750i
it's slightly not as good. but does the job so far. Maybe I should use my eVGA step up program and get a better MB

 

[Fumz]

Well the VID from what I understand is a way to tell what the Chip runs at stock speeds.. and ya they throttle down fine. ...

I don't know if I need to actually manually change my Core Volts. or if I need to add more to the NB or anything. but for now I'm ok at 3.4 I guess. I don't "NEED" anything higher, I just wanted to get higher for Benchmarks and such. thats all. but for 24/7 I'm probably just giong to stick with this.

... Maybe I should use my eVGA step up program and get a better MB

As long as it throttles down then you're all good. There's a link or two I'll throw up later that might help you get past Prime, but yeah, it's going to require upping voltages, so it may just not be worth it. For a suicide run ok, but not for 24/7.

I'd stick with the board you've got. 3.4GHz on a quad ain't half bad... lol... most would consider it "ok" or even "pretty good". It may just be that your chip's wall is in the 3.6GHz range? There's nothing a better board can do about that.

 

[xguntherc]

Ya True... well to be honest I am completely satisfied at 3.4 GHz. it runs great, games are great. and I'ts more than anyone needs. I just WANT to go higher. for obvious reasons and for benching. e-Peen. whatever peeps call it.

and ya I'm going to do a suicide run later tonight at 3.66 GHz with my 260 OC'd to 680 Core Clock and see what I get. and then for now on I'm stickin to calmer settings like 3.4

It's very possible that it's a wall I'm hitting. but your link above was very informative. and I'm giong to read it later tonight. I just got home from a lunch and had a few to many red bull and grey Gooses, not to mention a pitcher of beer. so time to relax before doing anything extreme..

Oh and lookin good there Fumz, if you didn't notice your name is now green.
Thanks to me for giving you some REP points. I give out 26 at a time I think. thats not bad. So I got ya above the mark for the green. I wanna get to the black, but it's going to take a while. lol

Thanks again!

 

[Fumz]

Aye... thanks for the bump. Green is good. I'll get to those links later... haven't forgotten.