Interesting observation on i7 clocking and DRAM voltage

[dejanh]

So I've been playing around pushing my i7 920 to or over 4.5GHz for 24/7 and so far I am up to 4.473GHz stable. Having said that, I noticed an interesting thing related to DRAM stability and DRAM voltage as I kept pushing my DRAM together with the CPU. Increasing DRAM voltage on my Corsair Dominator 1600MHz triple channel kit past 1.65V-1.66V actually has a detrimental effect on DRAM stability. I went as high as 1.7V but noticed that the closer I got to that voltage the more unstable the DRAM became and the more errors it would produce. This introduces an interesting conundrum in my efforts though since I am currently running my DRAM at about 1700MHz with my current OC and definitely going higher is not possible since 1.65V is not enough for increased DRAM speed but increasing the voltage only makes DRAM more unstable.

Why would just a tad more DRAM voltage past 1.65V actually have a negative effect :confused:

Looks like I am DRAM limited in my efforts to push onward :(

[Absolute_0]

Could just be the memory ICs not liking high volts... That or they are extremely sensitive to heat?

[rioja]

if u talk about 1600C8D, they can barely pass over 1600 and increasing voltage does not affect on them

[kromosto]

yes i got 3 single ocz 1333 cl9 1.7v

and can run them on i7 with 1900 cl8 1.8v without any problem

[Rudster816]

Whats your CPU VTT at? From what ive read your CPU VTT should be within .5v of your memory voltage.

The extra heat from the voltage could also be causing the instability. Thats the simple explanation

[dejanh]

Well, the modules do not feel very hot (just warm to the touch). The CPU gets no hotter really as the DRAM/VTT volts are increased. The VTT is within the 0.5V range. Highest stable Uncore is around 4.3GHz that I managed to get with this chip so considering that I am only running Uncore at ~4GHz it would not be a problem.

I do know that the original 1600C8Ds that I had could clock to 1900MHz, but after those died the replacement I got topped out at ~1800MHz with looser timings. I have not pushed my DRAM too high though ever for 24/7 since I used to run a i7 940. Now however I need to OC the DRAM to get the CPU OC higher as well in addition to just wanting to OC the DRAM anyway.

Maybe it does have something to do with heat, who knows...after all it is 35C here atm (ambient around the comp is about 40C :eek:). It's basically unbearable for me to sit at the comp atm.

[Leeghoofd]

My Corsair PC12800C8 ver 2.1 don't scale at all , mine even top at 1688Mhz at even C9 settings ( so you got a good kit there lol), Thorgal tested the rev 2.2 and these were far better ( link here : Mainstream I7 RAM roundup (http://www.madshrimps.be/?action=getarticle&number=18&artpage=4051&articID=893) look at the bottom of the page)

[Pyr0]

Yes, extremely disappointed with the Corsair Dominator PC12800C8 rev. 2.1 kit
From what I've seen even their cheaper XMS3 1600 C8 kits clock much higher

[dejanh]

My Corsair PC12800C8 ver 2.1 don't scale at all , mine even top at 1688Mhz at even C9 settings ( so you got a good kit there lol), Thorgal tested the rev 2.2 and these were far better ( link here : Mainstream I7 RAM roundup (http://www.madshrimps.be/?action=getarticle&number=18&artpage=4051&articID=893) look at the bottom of the page)

Thanks for that link. I am not sure what Corsair did to their DRAM after initial batches but the first batch of Dominators that I had way back when i7 just came out could comfortably clock to 1975MHz (granted this was at 9-9-9-24-1T, but still) from stock 1600MHz. The RMA sticks sucked terribly and the highest they go is 1800MHz but I never verified the stability when going so high. Two of my three sticks can still clock so high since they are from the original triple channel kit that clocked very nice.


Yes, extremely disappointed with the Corsair Dominator PC12800C8 rev. 2.1 kit
From what I've seen even their cheaper XMS3 1600 C8 kits clock much higher

Yeah, I'm thinking maybe to RMA these and ask Corsair for Rev. 2.2 as a replacement kit as per identification in the review above. Having said that, I was always a Muskin fan so I do not know why I even switched to Corsair now. Granted their support and warranty are not to be dismissed. My original RMA took less than 5 days, cross ship at Corsair's expense.

[Pyr0]

yeah, i foolishly thought all dominator mem was for overclockers
if i had known better i would have gone for cheaper sticks with better IC's

[burningrave101]

double post

[burningrave101]

Yeah, I'm thinking maybe to RMA these and ask Corsair for Rev. 2.2 as a replacement kit as per identification in the review above. Having said that, I was always a Muskin fan so I do not know why I even switched to Corsair now. Granted their support and warranty are not to be dismissed. My original RMA took less than 5 days, cross ship at Corsair's expense.

Yeah I just submitted an RMA ticket with Corsair to see if I can't do the same thing. My Rev 2.1 1600C8 kit does not overclock well at all. I wouldn't be surprised if they're what's been holding back my overclocks even when keeping them close to 1600Mhz. And I paid $324 for this kit back in December when DDR3 prices were still high so needless to say I haven't been very satisfied with them. If I can't get an RMA from Corsair then I'll probably switch to the Mushkin Redline 1600Mhz kit with rated timings of 6-7-6-18 which will do 2000Mhz.

[dejanh]

Yeah I just submitted an RMA ticket with Corsair to see if I can't do the same thing. My Rev 2.1 1600C8 kit does not overclock well at all. I wouldn't be surprised if they're what's been holding back my overclocks even when keeping them close to 1600Mhz. And I paid $324 for this kit back in December when DDR3 prices were still high so needless to say I haven't been very satisfied with them. If I can't get an RMA from Corsair then I'll probably switch to the Mushkin Redline 1600Mhz kit with rated timings of 6-7-6-18 which will do 2000Mhz.

Let me know how your RMA goes please :)

[Pyr0]

+1 :)

[dejanh]

Any updates on the RMA?

[rioja]

If I can't get an RMA from Corsair then I'll probably switch to the Mushkin Redline 1600Mhz kit with rated timings of 6-7-6-18 which will do 2000Mhz.

i changed 1600c8d to ocz reaper, which can 1600 c7 1.65 and 2000 9-9-9-30 1.65
and then to patriot viper 2 which can 2000 8-8-8-24 1.63 and 1600 6-6-6-16

but to be honest i could stay with first dominator coz i didnt get any benefit except austheteic

and dominators run very very cold comparing to last two, they get hot up to 50-60C

[IronAge]

DRAM depends on the design of the board and Bios code too.

For instance G.Skill Trident work like a charm on a Rampe II Extreme.

(6GB with DDR3-2000 7-8-7-24 works for many)

But they actually suck on the EVA X58 classified.

Before Gigabyte fixed a good bios they sucked on UD5 too.

[Pyr0]

no more news?

[burningrave101]

I got my Corsair RMA replacements today. I wound up with ver 3.2 so they're definitely new stock. They came in a nice looking retail package as well whereas my others that I bought back in December came in a plain brown box. I'll try and test them out some today and see how they clock.

[Pyr0]

anyone tried the ver3.2 kits?

[FabricioGS]

That's an intresting question. I think the fact of the memory controler be internal to the processor make things very much more complex than before. The vcore/vtt(uncore)/vdimm relation is very sensitive on those processors and if you miss the right proportion you'll have instability (with less or more voltage).

I just posted on another topic my 24/7 config: http://www.xtremesystems.org/forums/showthread.php?p=3964504#post3964504

I'm running 2000 9-8-9-26 and anytime I tried to up the vdimm I had issues. In the other hand I haven't tried stability with less vdimm yet.

[DavyBoy]

I have version 3.1 Dominator 1600C8D's, and they are extremely poor for clocking imo, I have tried running them slightly over their stock speed with looser timings (1688MHz with 9-9-9-26-2T timings) and I would experience BSOD as soon as I started running LinX...

I bought this RAM because I thought they would be decent for clocking, as I read a review online where they had them running @ 1800MHz with stock timings I think it was, but when I got mine and tested them out, I found that they struggled to do anything past their stock frequency...

When I got mine, I paid £165, but I wish I had done more research before buying, as I could have gotten something that performed better for less money!!

I would be interested to know how you get on with those replacement DIMM's though, if they are better, I might RMA my kit...

[Pyr0]

i've just had a spare hour to have a quick play with a ver3.2 kit, and they seem pretty good, scaling much better than the ver2.1's

i'm not going to try to say these are even remotely stable, but i managed 2000 8-8-8-24 with some extra voltage:
http://valid.canardpc.com/show_oc.php?id=663557
http://img36.imageshack.us/img36/9428/2000w.th.jpg (http://img36.imageshack.us/img36/9428/2000w.jpg)

and 9-9-9 with 1.66v, so there's prolly more in them.
http://img8.imageshack.us/img8/4870/200099924166.th.jpg (http://img8.imageshack.us/img8/4870/200099924166.jpg)

considering the 2.1's were a total letdown and wouldn't even post much higher than 1650, these sticks act completely different in every respect.