Some questions about QPI/Vtt and memory voltage/timings

[Major]

I've not built a new rig since my DFI NF4 Ultra and FX60 so I've been out of the scene for some time.

Just put the rig together a couple of weeks ago in my sig. Been working on the OC for the last week and have a couple of questions.

In order to get my Bclk stable at 210mhz I have to use 1.52v QPI/Vtt, I've seen several other using the same mb and Bloomfield processors acheive the same Bclk and higher using lower Vtt and some much lower in the neighborhood of 1.3v. I'm guessing since the memory controller is on the cpu that Bclk limits are determined by the cpu? or more of a mb limitation?

Also I'm running 7-8-7-24 timings at 1680mhz would the timings affect the required Vtt?

I've hit a wall at 212-213mhz Bclk and can't get stable at that speed regardless of Vtt or multiplier. Plus I'm already at a such a high Vtt that I'm affraid to go much higher. BTW the GB x58A-UD5 I'm using defaults at 1.52v when left at AUTO in bios and Blck is set to 200mhz.

[dinos22]

Hi mate

VTT can also be CPU and board related also. I would suggest trying to use 1.64vdimm from 1.5 its on currently and see if it allows you to lower VTT. The other thing you should look into is enabling turbo so that the CPU jumps to 21x multi hence using lower BCLK....btw BCLK does nothing for performance if you are thinking you need to have it high

also odd multies tend to be a bit more stable than even on Bloomfield

the OC looks good mate

[Biker]

Generally high QPI / VTT is needed on i7 boards when the ram is ramped up to 2000 and beyond...

For example my RIIE is only stable at DDR3 2100 with 1.57v QPI (1.52 real)...

I would say that 1.52 is high for DDR3 1680 but is that the real voltage being supplied?

A lot of i7 boards undervolt the QPI voltage by quite a lot so it would be best to check with a multimeter to see if your board is lying to you

Edit: + all of what dinos said

[Major]

Hi mate

VTT can also be CPU and board related also. I would suggest trying to use 1.64vdimm from 1.5 its on currently and see if it allows you to lower VTT. The other thing you should look into is enabling turbo so that the CPU jumps to 21x multi hence using lower BCLK....btw BCLK does nothing for performance if you are thinking you need to have it high

also odd multies tend to be a bit more stable than even on Bloomfield

the OC looks good mate

I orginally ran it at 21x200 for the first week or so but I discovered in OSX there seems to be qurik with having turbo on and using the 21x multi and it throttles the cpu somehow. My GL scores tanked, lower than default 2.66mhz so I've been tweaking to get my OC back using the 20x and turbo off.

I've not tried to loosen the memory timings yet and OC the memory much. And it was rated at 1.5v so thats what I've been running thorugh them.
G.Skill Pi series http://www.gskill.com/products.php?index=252

I'll try to up the voltage on them, but i read a review by Enjoy that talked like it was a waste of time trying to run them at anything but what was rated.
http://www.xtremesystems.org/forums/...d.php?t=245563

[dinos22]

ok fair enough

the OC looks good to me but it is a bit hot

maybe drop it down a notch......4GHz bloomfield is very powerful indeed

[Major]

ok fair enough

the OC looks good to me but it is a bit hot

maybe drop it down a notch......4GHz bloomfield is very powerful indeed

I like running it HOT......Killing it is the only way my wife will let me upgrade to a six core "Just don't tear this one up honey"

[Dopamin3]

I would not run higher than 1.45v VTT for 24/7. Especially for low memory speed like that (1680mhz) you should only need about 1.35v VTT or less until you get to really high BCLKs.

To overclock higher, why don't you just force the board to use the 21x multi all the time. Every bios implements this differently so you will have to see how to do it on yours. i7 often doesn't like even multis so that could be limiting you. Plus you can run BCLK lower to clock CPU higher.

[Capt Proton]

I've not built a new rig since my DFI NF4 Ultra and FX60 so I've been out of the scene for some time.

Just put the rig together a couple of weeks ago in my sig. Been working on the OC for the last week and have a couple of questions.

In order to get my Bclk stable at 210mhz I have to use 1.52v QPI/Vtt, I've seen several other using the same mb and Bloomfield processors acheive the same Bclk and higher using lower Vtt and some much lower in the neighborhood of 1.3v. I'm guessing since the memory controller is on the cpu that Bclk limits are determined by the cpu? or more of a mb limitation?

Also I'm running 7-8-7-24 timings at 1680mhz would the timings affect the required Vtt?

I've hit a wall at 212-213mhz Bclk and can't get stable at that speed regardless of Vtt or multiplier. Plus I'm already at a such a high Vtt that I'm affraid to go much higher. BTW the GB x58A-UD5 I'm using defaults at 1.52v when left at AUTO in bios and Blck is set to 200mhz.

Just a point of information. I am using a 1440X900 resolution on a 24" monitor. With that resolution and screen size (native is 1920 X 1200) I cannot make out your screen shot.

[Major]

I'll play around with it tonight and see if I can get OSX to work right using the 21x multi.
I'll also try messing around with the memory and Vdimm to see if it will let me lower the Vtt.

[trans am]

the general rule is:

the higher the bclk the lower you must run your qpi ratio to keep your ram stable.

say for example my ram can run fine at 7-7-7-24-1T@2000 mhz on 1.65vdimm on 150bclck but as soon as I raise the bclk to 210 or so it doesnt post even if I drop my cpu multi to a final cpu speed I know will work, it still doesn't.

regardless of voltage....

there is a known qpi/bclk/dram mhz wall around 200bclk or so. so that is why if you go to the extreme overclocking section and look at benches you will see a huge cpu oc but wonder why they used a 1600mhz ram frequency. you know damn well their ram is capable of pulling 2100 mhz at 8-8-8 / 6-9-6- etc but the only way to post is to run the ram at a dropped ratio and then tighen the timings as tight as a nuns private parts.
the 1st thing I would do is go in the bios and set defaults and hitf10 and reboot (assuming you have the latest bios installed)

then go into your oc settings and cpu/pci spread spectrum, disable speedstep, and the usual suspects. go to set oc via manual so you can start changing crap.
set you cpu multi and enable turbo and run qpi frequency at the 1st settting(lowest) just to begin. then do your ram timings and leave the rest on auto except change your vdimm to 1.65 and your vcore to 1.35 or so and see if it will post .

then you can start raising the bclk 5 or 10 mhz intervals and reboot if it doesnt take it start ramping up your vcore in the smallest increments( 1 or 2 settings up) get your bclk as high as you can and when you dont notice any changes regardless of voltage check what your ram is at and drop it down a step and try again. if it works then you can start raising your qpi up until you have it all maxed out. you can try taking the imc voltage off auto and trying a few or raise your cpu/pci clock drive 900/900 works well.

[jcool]

Lower your uncore mutiplier to 16x (=2x Dram). That will put your uncore at 3360Mhz, allowing you to use a lot less VTT ("QPI Voltage" is VTT really).

Why anyone would use OSX on a PC is beyond me though

[Major]

Why anyone would use OSX on a PC is beyond me though

Windows 7 does level the playing field and I find myself using it quite a bit, but once you have used Apple OSX it's tough going back to Microsoft.

[Major]

Lower your uncore mutiplier to 16x (=2x Dram). That will put your uncore at 3360Mhz, allowing you to use a lot less VTT ("QPI Voltage" is VTT really).

I'll try that this weekend

I've got everything working fine at 21x200 Linux and prime stable, but I would like to get 4.3ghz stable so I'll keep trying

[Major]

Lower your uncore mutiplier to 16x (=2x Dram). That will put your uncore at 3360Mhz, allowing you to use a lot less VTT ("QPI Voltage" is VTT really).

Ok, this was a home run!

I've been leaving the uncore multi setting to auto (since I'm a semi noob) and that has been one of the major issues causing me problems. I'm now running Vtt at 1.28v prime stable with the 2x rule (16x uncore). Even my temps are way down now

very cool! pardon the pun! lol

Ok, 1.22vtt is stable much better than previous 1.52vtt
I left Vcore bumped one notch to make sure it didn't cause any issues.

[donmarkoni]

Lower your uncore mutiplier to 16x (=2x Dram). That will put your uncore at 3360Mhz, allowing you to use a lot less VTT ("QPI Voltage" is VTT really).

This is a good advice for maximum overclock, BUT if you run UnCore @ 18x it will have a huge positive impact on memory bandwidth.

You can see the differences here: Mushkin Redline 1600 6-7-6-18-1T, especially 2nd screenshot where the settings differ from the rest and it has negative impact.

[jcool]

Be that as it may, running 1,5V VTT is NOT practical for 24/7 use.
i7 has more than enough bandwidth anyway for everything (not counting some benches).
I'm surprised no one else said anything about the Uncore multiplier earlier, but I am glad it worked for you Major

Donmarkoni, it really comes down to the individual CPU/memory combination. My w3520 could run 2Ghz Dram/4Ghz uncore easily with only ~1,34V VTT or so, but some chips just need excessive volts to go high on the uncore. No reason pushing them really (unless for short-term benching of course)

[PatRaceTin]

1.5+ QPI is too high for me

[Major]

Thanks for the help and advice guys!

I ran out of time last night but I'm at 4.3ghz Linx stable right now. I'm going to get what I can out of it

[Movieman]

I like running it HOT......Killing it is the only way my wife will let me upgrade to a six core "Just don't tear this one up honey"

Loved this one!

[donmarkoni]

Be that as it may, running 1,5V VTT is NOT practical for 24/7 use.
i7 has more than enough bandwidth anyway for everything (not counting some benches).
I'm surprised no one else said anything about the Uncore multiplier earlier, but I am glad it worked for you Major

Donmarkoni, it really comes down to the individual CPU/memory combination. My w3520 could run 2Ghz Dram/4Ghz uncore easily with only ~1,34V VTT or so, but some chips just need excessive volts to go high on the uncore. No reason pushing them really (unless for short-term benching of course)

I agree, of course. Those high voltages I used were just for benching.
I run UnCore @ 210x18=3780, VTT=1.376V as my 24/7 settings.
Great chip you got there.

[jcool]

3848A352.. it's for sale, by the way

[Major]

Well this is all she has in her (for now! lol)

21x208 4.36Ghz 1.350vcore

I've actuallly lowered Vtt down to 1.32v since I took this screen shot.

I can't get 4.4ghz out of it no matter what I try. My temps are good now so that's not an issue.

[PatRaceTin]

wow temp reach 80'Zone


what is your room temp?

[Major]

wow temp reach 80'Zone


what is your room temp?

We actually keep my office on the cold side, maybe 68-70F

I'm on air in a case, not a bench, not water cooled! lol

I'm happy with keeping it under 90c that is sorta my cut off point.

Right now I'm on my way to 4.5Ghz, at 4.4Ghz now running LinX as I type at 85c max.

I figured out a few things over the last 2 days and have a grasp on everything now.

I hope I don't kill my 920 just yet! lol may be a week or two before I can swing a 930 to try

Do you think 1.45vcore too much for 4.5Ghz on air (just for a bench not 24/7)

[donmarkoni]

Do you think 1.45vcore too much for 4.5Ghz on air (just for a bench not 24/7)

Nope. I would use 1.55V for 24/7 if I could cool it.