First time clocking 3770K - some basic questions need answers to

Flanno

Flanno

Flanno

Soldato
Joined
18 Jun 2005
Posts
3,434
Hi 8Pack,

I really need some advice on clocking my 3770K. Last time I overclocked was on Core2Quad so it's been a while. Have read all the guides on the forums but I have some very basic questions that I don't think were addressed.

Anyway, my spec is : Sabertooth Z77, 2x8gb G.Skill TridentX 2400mhz, 3770k, Phanteks TC14PE, (no gpu yet)

I want to use offset mode as I'd like to keep the cpu voltage / speed low when just browsing, but have it speed up when gaming.

To get an idea of how the things runs under stock speeds I left everything on defaults - cpu voltage auto, offset mode auto +, memory at stock DRR3 1333mhz, 1.5v. The only thing I changed was I set LLC to high (50%) and turned off cpu spread spectrum

I noticed the following and have a few questions

1. At stock, according to CPU-Z the cpu because of power saving idles at 1.6ghz, and takes around 1.11v. According to re Cores idle at 14, 25, 27, 16.

I thought perhaps the cpu sensor wasn't right because of the 10 degree discrepency (like what used happen on Core2's), so I ran the sensor test and everycore ran in mid 30's at 3.9ghz, and I also ran IBT and all the cores ran in mid 40's. So I assume there is nothing wrong with the sensors.

I wonder why is there a 10 degree discrepency between Core1/4 and Core2/3 at idle ? Are Core2 and 3 not being used ? Is it worth reseating the heatsink. I used the stock phanteks paste, pea sized blob on heatspreader.


2. When running at 3.9ghz (running IBT), the voltage drawn according to CPU-Z rises to 1.26v. So I changed the offset from auto +, to auto - and the voltage dropped to 1.2v at 3.9ghz. I imagine I can go lower at stock so will change the offset to - and some manual value (I think it's in 0.05v increments). However if I do this won't the voltage drop at idle too by same offset volts (when the cpu normally uses 1.11v at 1.6ghz), perhaps introducing instability ? Can I adjust LLC or some other setting to compensate ?

3. Assuming I can get it stable idle with lowest possible voltage, I will start overclocking. Is it best to increase the multiplier or increase the turbo ratio ?

4. Once I have the cpu stable and want to clock the memory, should I just use XMP and just go for 2400mhz. I realise I might have to tune some settings to get it stable. Any advice ?

Thanks
 
Thanks for the excellent advice 8Pack.

Had a quick play this evening. Only had realtemp, cpu-z, and ibt at hand as internet fiddly tonight. Is IBT safe by the way as you mentioned on another thread that Intel engineers cringe when they hear about us using it :)

Anyway, just concentrating on the cpu tonight and I found at 44 ratio my bios wanted 1.354v and with LLC at high (50%), it went to 1.496 within seconds of doing a normal IBT run (regardless of whether offset is set to +/- auto). At 42, the bios only wanted 1.180v which translated to 1.328v within seconds of putting the chip under load.

In the end I settled for a manual negative offset of -0.065v (interesting that the bios highlights this number in red while -0.060v is fine). This gets me to 1.216v under load at 4.2ghz.

I did 10 runs of Intel IBT at very high, and all 4 cores maxed between 58 and 62 according to realtemp. Core 3 was the hottest at 62 (Core 2 in Core Temp terms). I was surprised at this as Core 1 and 4 idle at 25 and 2 and 3 idle at 15!! So I had expected 1 and 4 to be much hotter under load. Guess it doesn't matter and no need to reseat the heatsink thankfully.

I have left VCCSA, VCCIO and PLL all at auto.
Is LLC good enough at 50% (high) or should I lower it considering the high offset (I assume) that I am using ?

thanks
 
Interesting mate but a + offset is a no go on my chip as with a 44 or 45 multi the bios wants 1.354v and this only goes up under load to nearly 1.5v (according to CPU-Z) with LLC at high (50%). That's why I had to use a negative offset of 0.065v.

I have not looked at PLL yet. What does adjusting this affect ? Hopefully it reduces current draw/temps by lowering it ?

Also I have Asus multicore enhancement disabled. How is this different from Intel's version ?

And should I turn off Internal PLL Overvoltage. Read it's only need for very high multi's ?

Sorry for all the questions mate.

thanks
 
Last edited:
Ah Ok. I think I get it.

So offset set to auto just lets the motherboard supply what it thinks the chip needs.

So I will try +0.05 and report back.

However, in offset mode why is it I needed to use -0.065 at 4.2ghz to keep my cpu around 1.216v ? I assume this is because my cpu requests a high vcore at 4.2ghz and not 1.2v as I would have expected. I am also thinking in this scenario because of the high offset I should have used a low LLC to allow the voltage under load to drop to around 1.2v.

Anyway, I will try what you suggested and report back shortly.

Thanks
 
Heheh...that's exactly what I have done. Running at 4.4ghz now, have IBT running overnight (I hope).

My chip is hungry and can request up to 1.496v in offset mode under load at 4.4ghz. So a negative offset was needed to bring it down to 1.25v.

I found this to be a very interesting post on vdroop and LLC, where the author recommends a low LLC.

http://forum.overclock3d.net/showthread.php?t=46502


Should I mess with PLL or leave on auto and is it ok to turn off PLL overvoltage ?

thanks
 
Actually you just reminded me to go back and check what the stock voltage is again. You see I had LLC at high, so when I but system underload at stock 3.9ghz it was 1.26v (up from 1.11v at 1.6ghz). Doesn't LLC add voltage ? So perhaps if LLC is set to auto and I check stock again it might be lower. Hmm... I suppose it doesn't matter really because it ran IBT under heavy load overnight and I never saw any core go over 64 degrees at 4.4ghz @ around 1.25v.
 
Don't you think I know to use my pc for testing. But some of us actually work nights or have to be up at 4am in the morning so no opportunity to use my pc for testing after I clocked it last night. IBT was a quick way of testing it. I will use Memtest from now on I guess.
 
You must log in or register to reply here.
Back
Top Bottom