skt1155 and memory voltage?

paradisiac · 25 Jun 2011 at 20:36

so whats the deal with SB only liking 1.5v-1.55v? what will happen with my 1.64/1.65v ram? instability or less overclocking potential?

cmndr_andi · 25 Jun 2011 at 20:38

From the sandy bridge OC info thread (which uses info direct from intel and OCUk shop experience):

Memory - Intel recommend 1.50v plus/minus 5% which means 1.60v is the ideal safe maximum, but we have found in our testing all 1.65v memory is fine. We have also found most new 1.65v like Corsair XMS3 will run at its rated timings with just 1.50-1.55v which is well within Intel specifications. So people upgrading to Sandybridge you can still use your old DDR3, but we do recommend you run it at 1.60v or less. We are shipping most of our bundles which feature Corsair XMS at 1.50v-1.55v at rated timings. We've also discussed with Asus and MSI regarding voltages for memory and they also confirm in their testing 1.65v caused no issues with reliability.

paradisiac · 25 Jun 2011 at 20:41

mine have been running fine for a week now with my G620, so it should be ok when my 2500k comes on monday, or should i play with the timings to get the voltages down?

cmndr_andi · 25 Jun 2011 at 20:45

I believe the risk of higher memory voltage is long term reliability (ie CPU life). Personally I would spend the (most lilely very small) time required to get the voltage within spec (even if that means dropping the frequency down to 1333MHz - the real performance drop is tiny).

I would suggest running CPU-Z and looking in the SPD tab - this will show you what profiles your RAM is rated to run at. Since it is a DDR3 kit then more than likely one of these rated profiles will use a voltage of 1.5V.

paradisiac · 25 Jun 2011 at 20:49

cmndr_andi said:
I believe the risk of higher memory voltage is long term reliability (ie CPU life). Personally I would spend the (most lilely very small) time required to get the voltage within spec (even if that means dropping the frequency down to 1333MHz - the real performance drop is tiny).

I would suggest running CPU-Z and looking in the SPD tab - this will show you what profiles your RAM is rated to run at. Since it is a DDR3 kit then more than likely one of these rated profiles will use a voltage of 1.5V.

they are 1333mhz anyways :confused:

but this is even more confusing :

TEAMGROUP said:
Specification Content
Suitable for : Desktop PCs
Module Type : 240Pin Unbuffered DIMM Non ECC
DRAM Density : 128x8,256x8
Data transfer bandwidth : 10,664MB/Sec (PC3 10660)
CL-value : 9-9-9-24
Working voltage : 1.5V±0.075V
PCB : 6-layers PCB
Extra features : Yes
Warranty : Lifetime warranty

so why does the XMP and bios auto run it at 1.64/1.65v?

cmndr_andi · 25 Jun 2011 at 21:02

Ha, that is pretty funny.

In that case you should have no issue running that kit at 1.5V and with a sandy bridge system.

As for why XMP sets it to 1.65V, I have no idea. Does this setting achieve tighter timings than 9-9-9-24 @1.5V? Perhaps it was a marketing thing - as all Nahalem memory kits were 1.65V and they didn't want to fell left out and look inferior to people comparing product descriptions (bigger numbers are better).

paradisiac · 25 Jun 2011 at 21:04

cmndr_andi said:
Ha, that is pretty funny.

In that case you should have no issue running that kit at 1.5V and with a sandy bridge system.

As for why XMP sets it to 1.65V, I have no idea. Does this setting achieve tighter timings than 9-9-9-24 @1.5V?

nope, still 9-9-9-24 :confused:

so i guess i just manually set it to that and drop the voltage and im good to go?
but i have noticed in the SPD tab it says it should be 9-9-9-25 :confused:

think something isnt detecting it right.

cmndr_andi · 25 Jun 2011 at 21:07

Aye, based on those specs from the manufacturer you should be able to enter the settings manually and not have any trouble.

Data transfer bandwidth : 10,664MB/Sec (PC3 10660)
CL-value : 9-9-9-24
Working voltage : 1.5V±0.075V

paradisiac · 25 Jun 2011 at 21:10

cmndr_andi said:
Aye, based on those specs from the manufacturer you should be able to enter the settings manually and not have any trouble.

awesome, had a proper panic attack when i read my ram might be too high a voltage after shelling out on all my bits (ram was recycled from my old AMD system)

Speed · 25 Jun 2011 at 21:15

cmndr_andi said:
I believe the risk of higher memory voltage is long term reliability (ie CPU life).

+1. Worth pointing out that they are just Intel recommendations and there is no proof that 1.65v modules cause problems. It might be that the die shrink has also affected the onboard memory controller, but I'm not sure.

paradisiac said:
nope, still 9-9-9-24 so i guess i just manually set it to that and drop the voltage and im good to go?
but i have noticed in the SPD tab it says it should be 9-9-9-25 think something isnt detecting it right.

Yup. Just make sure you test it with Memtest86+ to make sure there are no errors, 2 passes is enough.

Justintime · 25 Jun 2011 at 21:51

Transplanted some Ripjaw CAS 7 1600MHz from my 920 rig to my 2600k and they still do advertised speed at 1.5v, i think rated was 1.6-1.65v, over a year old.

paradisiac · 26 Jun 2011 at 11:29

set it to 1.5v and all seems good

not sure why it doesnt do that by default :confused:

is it worth trying to get anymore from my ram like 7-7-7-21 or will it not make a huge difference?

Speed · 26 Jun 2011 at 13:14

paradisiac said:
set it to 1.5v and all seems good not sure why it doesnt do that by default is it worth trying to get anymore from my ram like 7-7-7-21 or will it not make a huge difference?

I expect the memory was designed with X58 and other older chipsets in mind which seem to require more voltage. Sandy Bridge is pretty new. I did the same with my Mushkin Copperhead on a P67 board, rated for 1.65v @ timings/speed written on the side but runs fine at 1.5v using the same timings/speed.