Help in understanding V-core

[p3matty]

I've read through many of these forums, and am currently trying to get either a MO stepping E2140 or an L2 stepping E2160 to 3.0 GHz (as it's a good, round number that I didn't think would be so difficult).

For the last few months, I've had the E2140 at 2.67 GHz (333x8), and very stable. This was simply done by changing the FSB in the BIOS on my Asus P5K-E WIFI from "stock" 200 to 333. Nothing else was done, no "tweaks" to voltages or nothing.....easy as pie.

Fast forward a few months, and my folks want a new computer, and I offer to build it for them. As really all they do is e-mail / spread sheets / and tax software, I didn't have to go top end at all. I thought I would get a new E2160 for myself, and build their's around my slightly broken in E2140. My thinking was that at the same 333 FSB, the E2160 would go right to 3.0 Ghz, my target. I first booted at 266 FSB (2.4 GHz), still on stock cooler, and it's fine. I then upped it to 300 (right where the E2140 was before with no issues), and I get BSOD. I guess the L2 E2160 won't OC as well as the MO E2140.

I guess to go any higher, I will have to start messing with the voltages, which I didn't want to do. I also ordered an Arctic Cooler Freezer 7, to help with the higher temps. First off, what is "auto" technically set to on my board? I know I can read it on CPU-Z or Coretemp, but those two values are different, and neither know what my boards V-droop is (another term I'm unfamiliar with).

When I start upping my voltages (hopefully it will just be the V-core, and nothing else) where should I start, and how high should I go safely?

Thanks, and if you need any other information, I'll be happy to give you what I can....

 

[Lupiron]

Auto is the factory defaults programmed into the cpu and ram. For example, my quad 6600 b3 is a 1.3125 volt VID. So on auto, the board will set the voltage max at that, though when you see it in windows, vdroop and vdrop make it lower. Thats a saftey feature so that the peak power only reaches that VID.

As in, 1.3125 in windows is 1.27, and it goes down further as you use power based on load. So when you have your CPU running at full capacity, and then you decide to just click the close window option on whatever program that was using the CPU. The power supply cant instantly stop sending that power, so there is a possibility of your CPU drawing that same amount of current for a split second after you terminate the program.

So its lower than the VID by a bit, just to be safe.

By the way, alot of time when things are on Auto, and you OC, the board automatically over volts stuff as you OC. Just remember, as you get familiar with OCing, you'll note that most if not all of the auto voltages tend to actually go up more than you need.

--Lupi

 

[Perp]

Depending on what ram you purchased going for a 1:2 ratio is a good start. For example if you have DDR2-800, try getting a 400mhz FSB in the bios with a 1:2 ratio that gives you 800mhz ram. This would put your CPU at 3.2 with an 8x multiplier (both chips you listed have access to 8x multiplier). Of course you'll have to bump the voltage a bit to hit 3.2 with the CPU, but by how much really depends on your specific chip.

 

[Lupiron]

Perpster!

Hehe!

 

[p3matty]

I'd like to do 333x9 on the E2160 is possible, as this is stock for the MOBO, and will still let me run my RAM (Corsair XMS) at 800 with a 5:6 divider. Since it seems that I'll have to start tweaking the voltages to get there, I just wanted some help on where to start in that process.

Correct me if I'm wrong, but won't it be easier to get to 333x9 than to 375x8? I know both will get you to 3.0, which is where I'd like to end up, but the 333 fsb is still stock on the MOBO, and lets me run my RAM either at 800 (5:6) or at 835 (4:5). If I were to go to 375, my RAM options would be 750 (1:1) or 900 (5:6). The two options at fsb 333 give me the two better options I think.

 

[Evilonigiri]

According to Anandtech, they explained that there would be no difference between 333x9 and 375x8 in most real world applications. Thus if you just play games or such, it's pointless to set it to 375x8.

 

[p3matty]

^ That's my point. Why set it to 375, when it's easier and no different to set it at 333 with a higher multiplier? My question comes down to where should I start my user-set CPU voltage in BIOS? I mean, what's "stock" on these chips? And how high can I bump it up and still be safe?

 

[Evilonigiri]

Anandtech also explains why people still use higher fsb with a lower multiplier. This is because back in the days mobos didn't have an option to change the tRD timings. Because of this, higher fsb will bring more performance.

These days, the timings are adjustable so there's no need to raise the fsb to bring more performance. However the old timers still believe that higher fsb will bring more performance like before.

To answer your question, you should start at 1.300V for 3GHz. The highest you can set it and still consider it to be safe is 1.5V, but watch out for the temps.

 

[p3matty]

Thanks!! I'm hoping to be able to get to 3.0 with only tweaking the CPU voltage, nothing else, as I'm really not that familiar with anything else. I did get an Arctic Cooling Freezer 7, so hopefully that will keep my temps down. I understand (for the most part) the overclocking guide here, and plan on following it, just didn't know where to start my V-core level to keep things safe and roughly about where it would need to be for this overclock.

So, you're saying start at 1.300V in the BIOS for the Asus board? I'll do that and see if it's stable. If so, start lowering....

 

[Lupiron]

So, you are telling me that you'd rather run yer ram slower because faster doesnt matter?? Wow, i Love it, maybe to you it doesnt, but when you remain in sync and get a faster speed, I'll bet it does!

--Lupi!

 

[Evilonigiri]

Lupi, I did say for most applications you won't see a difference. Especially games I'm sure.

 

[p3matty]

Lupi, at a FSB of 333, I can run my RAM right at 800 mhz, which is what it's rated for.

If I were to use a higher FSB (375 for instance), I would have to run my RAM at 750 or 900 mhz. This means either overclocking my MOBO and underclocking the RAM, or oveclocking both.

I'm hoping to get by with only overclocking the CPU, and leaving the MOBO and RAM both at stock. Going with a fsb of 333 allows me to do that.

Am I missing something here?

 

[Evilonigiri]

There's nothing wrong with underclocking. What Lupi likes to do is set fsb to ram ratio to 1:1. Thus if he wanted 3GHz and 800MHz ram, he'd have to do 400MHz fsb. After all, there are reports that 1:1 ratio brings the best performance.

 

[Lupiron]

Hey man, now you know why! Lesson of the week. But I suppose that most people wouldn't need it anyways. Or notice. ::Kicks as many people as he can, right in their swap file.:: Get rid of that thing and see how ram speed really works!

I guess thats one point for vista 64! 8 gigs is enough to ditch that swap file, and stop windows from writing ram out to disk! As I am sure you all are aware, the difference in speed between a disk drive, and RAM is like a slug to a cheetah! No more faulting to the disk = no more bottle neck there. And since everything remains in active memory, the faster the RAM the better your overall performance will be!

Oh, how impressive! in a 7 min or so test, 4-4-4-12 yielded a six second gain. (Did several tests, and 6 seconds was the smallest, 8 being the highest. The amount of active background progies in busy body windows accounts for the difference, but I go with the worse number.)

All I did to test is a bunch of instances of 16 million decimal super pi with my ram, 1066 kingston hyperx 5-5-5-15, in sync at 800 @ both cls5 and 4. That was the results.

I assume that when running a continuous program that forces data through the ram fast, the results would be worse than a bunch of small data passing through the RAM. So for daily activities, not that you would prolly notice to much of a difference. But i'll wager that your computer would notice the difference.

Wait, I am getting off track!

No free lessons!

--Lupi!

 

[p3matty]

Thanks for the lesson!! Just to keep things simple, though, I did 333x9 last night at 1.3000 in BIOS. It didn't even boot up....

So back into BIOS and I went right up to 1.3500 in BIOS, and it booted. Ran PRIME95 on both cores, and got an error message after 10 minutes or so. Back to BIOS and upped it one notch, error in about 2 hours. Bumped it one more, up to like 1.3750 or something. Ran testing for 8+ hours, no problems, so I think I found my sweet spot.

A few questions, though...
1) While it's 1.3750 in BIOS, it only reads as like 1.32... or so in CPUZ, FanSpeed, and other programs when under load, and a bit higher than that at idle. Which is accurate? When people say they have their's at a certain vcore, which are they referring to? Is this level still safe?

2) As I just wanted to be able to set it up quickly, I removed the old Arctic Silver 5 from the CPU as best as I could with a coffee filter (no cleaning solution or anything), and simply left the substance on the Arctic Cooling Freezer 7 that it shipped with. Is this ok, or should I remove both to clean and apply fresh AS5? If so, what should be used to clean both the CPU and the heat sink?

3) This might sound like a stupid question, and I think I know the answer, just making sure. Does better cooling allow you to run at a lower Vcore stably? I would think that no, you have to run at a certain Vcore to stay stable, the cooling simply allows you to run at that higher Vcore with a lower temperature. Do I understand this properly, or not?

Again, thanks for the help!!

 

[Dunkel]

1) 1.375V is great for 3.0GHz OC. I run my E2160 @ 356x9, 1.4875V. The difference in CPUz V is due to Vdroop. Nothing to be concerned about. I think the CPUz V is the actual voltage going to your chip. Which is why, with chips rated at 1.5V max, you can set it to >1.5V in BIOS. Once windows is running the voltage will be below 1.5V in CPUZ.

2) This is ok. The Freezer 7 ships with a very good thermal compound pre applied. You will know if you need to reapply in a week or so if your load temps go above 70C.

3) You are correct.

 

[p3matty]

Great, thanks!! It sounds like I'm good to go!! I knew that I most likely could go beyond 3.0 ghz, but I didn't really want to. It's a nice round number, gets me roughly the same performance as the $200+ chips, and will still last me a few years before an upgrade. I just didn't want to decrease the lifespan of any of the other parts.

Oh, and even after 24 hours of stress testing in a fairly warm room, the temps didn't go above 55C. Now, these temps were from Speed Fan after I calibrated it using the guide here. One question I had about that is do these chips really only idle 2-4C above ambient at stock idle? That just seems extremely low to me!!

 

[Dunkel]

They will idle that low if you followed the guide. Meaning, turning things on that you would normally have off for OCing, having your CPU fan at Max, and the side off your case. Then make sure you know what your room temp is. Add a couple of degrees when you calibrate SpeedFan and you'll not have to worry about temps ever again. Unless they go over 70C that is.

 

[p3matty]

I never hit 60 on the stock cooler, and haven't hit 55 at a higher OC with the ACF7.

 

[Dunkel]

There's a lot of controversy with CPU Temp monitoring apps. I believe if you follow the sticky Temp Guide to calibrate speedfan, you will be ok. It sounds like you are ok now, but every set up is different. 3.0 is a good place to be with that chip. If you shoot for 3.2 you'll get it with time but then you will want 3.4 which I can't do . I took my CPU voltage to 1.6V in BIOS and still couldn't post.

 

[Evilonigiri]

I just underclock my Q6600 from 3.15GHz to 2.10GHz, using the setting 9x350 and 6x350 respectively. I just wanted to see how effective Speedstep is, after all that's what Speedstep does, bring the x9 multiplier to a x6 multiplier.

My idle temps dropped 10C. Imagine that. 9x350 with speedstep (so effectively 6x350) idles at 40C while 6x350 idles at 30C. Makes me think that speedstep is rather pointless. Vcore at 6x350 is .9875, 15hours small FFT stable. Never broke over 42C. Before at 9x350, it went above 70C due to the hotter weather.

 

[Dunkel]

 

[Lupiron]

Yawn!