PDA

View Full Version : 24/7 Safe OC for the 920 ?


Logical
01-13-09, 09:43 AM
I have seen reports that the core i7 920 is completly safe at 4Ghz @ 1.4-1.46v. Others i have read have suggested that anything above 1.4v is shortening the life of the i7 chip and now i have seen rumours that the uncore and vdimm can also affect the CPU.

Lets face it from 2.6 to 4.0 is a massive leap and leaves me wondering why Intel hadn't shipped them with better if not slightly better clock speeds to start off with.

I am getting my new system soon and will want to be overclocking it to a safe and stable 24/7 oc, i will also be using the TRUE 120 to cool it and 1600mhz corsair dominator cas 8 on the EVGA mobo.

I have read Jacobs overclocking guide on the EVGA forums and it seems with a 20x multiplier 4.0Ghz is easily acheived. I just need more opinions and suggestions for an overall piece of mind before i overclcok.

Edit: Sorry can a mod move this to correct forum please. :)

eva2000
01-13-09, 11:35 AM
I'd keep vcore <1.35v for 24/7 and as to mem voltages, key to vdimm>1.65v is to keep uncore voltage is within 0.5v of dram voltage - this info comes straight from Intel themselves via bit-tech.com's P6T Deluxe article

http://i4memory.com/wp/article/191
http://i4memory.com/wp/article/327

uncore = CPU VTT or on P6T Deluxe called QPI/DRAM

max CPU VTT 1.35v is intel recommendation too, so at most you'd have 1.5-1.85v range for vdimm

Logical
01-13-09, 12:25 PM
The corsair 1600mhz ram has a max voltage rating of 1.65v so if i have vdimm at 1.65 and set the uncore (cpu vtt) to +250mv i get almost the max VTT of 1.35v. Is this correct?

If this is the case then in all situations of setting the ram to specified frequency or indeed overclocking it then the uncore (CPU VTT) HAS to be changed accordingly, even if the CPU core is not being overclocked.

Thats quite an important factor for anyone running anything above 1333mhz ram @ 1.5v.

Toss3
01-13-09, 12:54 PM
The corsair 1600mhz ram has a max voltage rating of 1.65v so if i have vdimm at 1.65 and set the uncore (cpu vtt) to -350mv i get almost the max VTT of 1.3v. Is this correct?

If this is the case then in all situations of setting the ram to specified frequency or indeed overclocking it then the uncore (CPU VTT) HAS to be changed accordingly, even if the CPU core is not being overclocked.

Thats quite an important factor for anyone running anything above 1333mhz ram @ 1.5v.

Wow thanks for pointing that out! :) Should be getting my 920 tomorrow and that's the first time I've heard about it! :o

From Bit-tech (http://www.bit-tech.net/hardware/2008/11/06/overclocking-intel-core-i7-920/3):

While Asus and Intel (rightly) scare everyone (read: uneducated) into thinking that 1.65V on the DRAM voltage should be the absolute limit before you reach for the fire-blanket, all that's really needed it to obey this: keep the CPU uncore voltage within 0.5V difference of the DRAM voltage and there's no problem. Over this potential difference and you’ll greatly increase the chance of CPU death, but it certainly won't happen instantly in a big ball of fail fire if you make a mistake

Logical
01-19-09, 10:01 PM
Got my wires crossed seems that the default VTT is 1.1v

Edited my last post for correction :)