Haswell Voltage Question

On my last i7 920 build, I had some Corsair 1600Mhz XMS 1.65v Ram with a Asus P6T. However, when I enabled the XMP profile it would bump the Dram Bus Voltage up to 1.66v and it worried me due to all the warnings! I ended up running it at 1333Mhz just to be safe. I know it was probably okay but I didn't want to gradually fry my memory controller.

 

I'm now building a new Haswell i7 4770 (probably non-k). I'm looking at this RAM:

 

CMY16GX3M2A1600C9 or CMY16GX3M2A1866C9

 

My questions:

1) With the XMP profile enabled will both of these run at 1.5v or will it get bumped up again to 1.66v?

2) I don't plan to overclock, so can I still benefit from 1866Mhz memory or should I just get the 1600Mhz? I may still get the K version of the CPU if the price is right.

3) If I got the 1866Mhz memory, is there also an XMP setting for 1600Mhz? Or does each set have just one XMP profile.

 

Sorry for the noob questions.

 

Thanks in advance!

if you dont OC and plan using it as stock then the 1600 will do just fine,contrary to what some will say,i feel the difference from 1600 to 1866 is very marginal...

you may consider the k model just in case you change your mind

i got the 2600 on the same premise and later on wished id gotten the k

I would consider the k model just for resale ability. Your market for resale will be substantially smaller. As for those kits I believe they are both 1.5v. Xmp is just a memory profile not an overclock tool. It just makes sure all settings are correct for the sticks to run at optimal settings.

What wytnyt said is correct. 1600mhz vs higher speeds has a very minimal difference as most higher speed kits will have higher timing as well which kind of negates the speed difference. 1600 cas 9 vs 1866 cas 10 vs 2133 cas 11 is pretty much the same.

If i was you due to the 1866 kit being cas 9 I'd go with it. Otherwise get whatever kit looks best with whatever motherboard you get.

Thanks for the help wytnyt and HOODedAssault. I may get the K, although I don't tend to sell my CPUs on, they tend to get passed onto family members etc.

 

So from what you are saying, it should keep the Dram Bus Voltage to 1.5 if I run either of these kits with their XMP (1600 or 1866)? I was just worried as my last Corsair memory was rated at 1.65v and the bios gave me loads of warnings about breaking the memory controller as the XMP set it to 1.66v.

 

Thanks again :)

Ya both those kits were basically built for haswell so they are 1.5v. If you need more volts than its a bad kit. You'll be fine with either at 1.5v and rated specs. 1st gen i7 are rated for 1.65v just fine, sandybridge and everything after are rated for 1.5v.

Thanks! That makes things clearer :)

I just ordered the CMY16GX3M2A1866C9 kit - it was only £136 delivered from Dabs, so seems like a good price :)

 

http://www.dabs.com/products/corsair-16gb--2-x-8gb--vengeance-pro-black-ddr3-1866mhz-cl9-8QJ5.html

 

Thanks for all the advice.

Ya both those kits were basically built for haswell so they are 1.5v. If you need more volts than its a bad kit. You'll be fine with either at 1.5v and rated specs. 1st gen i7 are rated for 1.65v just fine, sandybridge and everything after are rated for 1.5v.

Socket 2011 and Haswell both use 1.65v memory . That was one of the changes back from Sandybridge. As long as you stay within JDEC specs your fine.

 

Originally pposted by:russd1978

So from what you are saying, it should keep the Dram Bus Voltage to 1.5 if I run either of these kits with their XMP (1600 or 1866)? I was just worried as my last Corsair memory was rated at 1.65v and the bios gave me loads of warnings about breaking the memory controller as the XMP set it to 1.66v.

Correct and your BIOS will give you a warning anytime you change a setting from a default number. It's just making sure you know what you are doing before hand. It will eventually go to yellow and then purple , I think was the order once you get in to the really high range. But 1.65v isn't going to hurt a thing. As long as you have a good CPU cooler, your good to go. Alot of Corsair's Haswell kits are rated for 1.65v at the XMP settings.

 

As a side note XMP will also adjust other BIOS settings depending on how of an overclock you have. CPU and IMC voltage adjustments are not uncommon.

Thanks - strangely on my old P6T it only does the voltage in 0.02 increments. So the XMP sets it to 1.65 but the P6T nudges it to 1.66v and then warns me that I'm over the 1.65v recommendation.

 

I can set it to 1.64v and that seems to work okay without any warnings. Haven't noticed any problems whilst the PC is running like this. Manually typing in 1.65 doesnt work (it just changes it to 1.66v) so to be safe I set it to 1.64v.

I know they can handle 1.65v easily. I've personally ran 1.65v ram without issue on 3770k 2500k 2600k 3930k and 4770k without issue. But I'm pretty sure intel recommended spec is 1.5v and y would the xmp profile be 1.65v. Xmp profile should go by whatever it says on the ram 1.5v 9-10-9-27 1866 which is spec for ram op purchased. Most ram will actually run stable lower when rated at 1.65v. My Kingston 4x4gb kit actually ran perfectly stable (mem test tested) at 1.56v. That's not guaranteed tho.

Yeah good point - its just a shame my Asus mobo only allows 1.64v or 1.66v - it won't run at 1.65v for some strange reason!

I always ran 1.64v on all my 1st gen setups. Every board I've ever used was actually slightly higher then set. 1.5v ends up being 1.51-1.52v on every board I've used. Probably done on purpose to guarantee stability. I had a p6t Se crossflashed to p6t for sli support and ran it at 1.64v with no issue for years.

But I'm pretty sure intel recommended spec is 1.5v and y would the xmp profile be 1.65v. Xmp profile should go by whatever it says on the ram 1.5v 9-10-9-27 1866 which is spec for ram op purchased.

Hooded you need to pay attention to your memory specs. You have a SPD and an XMP settings. It all depends on the kit. Some are 1866 at 1.5 and some are 1866 at 1.65v. These are listed in the tech specs for every kit.

 

What is the exact part number of the kit your using?

 

As far as the MB only allowing 1.65 to 1.66v, ,my board did that too. It was changed in the very last BIOS update. So if you don't have the latest BIOS you might want to update. But it doesn't matter either way. .

Hooded you need to pay attention to your memory specs. You have a SPD and an XMP settings. It all depends on the kit. Some are 1866 at 1.5 and some are 1866 at 1.65v. These are listed in the tech specs for every kit.

 

What is the exact part number of the kit your using?

 

As far as the MB only allowing 1.65 to 1.66v, ,my board did that too. It was changed in the very last BIOS update. So if you don't have the latest BIOS you might want to update. But it doesn't matter either way. .

 

I'm confused but I found haswell spec sheet and it says 1.5v for ram. Go to page 18. I still agree its not going to hurt the chip at 1.65v tho.

http://www.intel.com/content/dam/www/public/us/en/documents/datasheets/4th-gen-core-family-desktop-vol-1-datasheet.pdf

 

Sorry I don't really understand what your asking. I'm just saying that in my experience most boards I've used actually go up slightly in voltage from what is set. So using 1.64v if you only have the option for 1.64 or 1.66 should be fine. Even 1.66v would be fine on 1st gen i7 tho.

 

Anways I think were way off topic here as OP has already bought his ram kit lol.

I'm confused but I found haswell spec sheet and it says 1.5v for ram. Go to page 18. I still agree its not going to hurt the chip at 1.65v tho.

http://www.intel.com/content/dam/www...-datasheet.pdf

 

 

I'm going to quote someone else's post just because of the amount of information contained within...that and I can't explain it any better :P

 

Also please read the links contained in there too! :)

http://www.tomshardware.com/answers/id-1698560/65v-ram-haswell.html#10941292

 

1.65v RAM does NOT void your warranty! :)

I agree 1.65v is fine. Sandy and ivy had a lot more 1.65v ram kits around. Since Haswell I have seen a lot more 1.5v high speed kits available. Makes sense for someone who is reusing a ram kit from an old system in their new Haswell setup. I don't see why anybody would run 1.65v ram nowadays in Haswell if buying new. Maybe if it's 2400mhz or 2666mhz. Even if those speeds are completely useless for everyday use, most I've seen are rated for 1.65v for that high of speed. Going 1.65v on 1600mhz- 2133mhz is useless tho. Over works imc and makes cpu run slightly hotter.

I agree 1.65v is fine. Sandy and ivy had a lot more 1.65v ram kits around. Since Haswell I have seen a lot more 1.5v high speed kits available. Makes sense for someone who is reusing a ram kit from an old system in their new Haswell setup. I don't see why anybody would run 1.65v ram nowadays in Haswell if buying new. Maybe if it's 2400mhz or 2666mhz. Even if those speeds are completely useless for everyday use, most I've seen are rated for 1.65v for that high of speed. Going 1.65v on 1600mhz- 2133mhz is useless tho. Over works imc and makes cpu run slightly hotter.

 

Yes, good points.

 

Personally, I'd rather have something running 1.5v - not because its dangerous to run at 1.65, but because I'm not 100% certain the new motherboard I choose won't do the p6t thing of only offering 1.64v or 1.66v - very strange behaviour. I know you say it doesn't matter but I like to keep things simple. As you say, doesn't seem to happen now, but I'd rather not leave anything to chance.

 

In case you're wondering, here's my build:

http://uk.pcpartpicker.com/user/russ1717/saved/3Ndi

 

I did go with the K version in the end, as you never know if OC'ing will be something I want to do later on.

Personally, I'd rather have something running 1.5v - not because its dangerous to run at 1.65, but because I'm not 100% certain the new motherboard I choose won't do the p6t thing of only offering 1.64v or 1.66v - very strange behaviour. I know you say it doesn't matter but I like to keep things simple. As you say, doesn't seem to happen now, but I'd rather not leave anything to chance.

Have you ever updated the BIOS on your P6T? My P6X58D-Premium did that when it was new. They changed that in a BIOS update and gave me the option to go in .1v increments instead of .2v's. It's pretty common with the ASUS boards...At least the older ones.

 

But as far as keeping things simple, I think is a wise choice. 1866mhz is a small OC and should perform very well for you.

 

 

I understand wanting to stay at 1.5v, and I agree you shouldn't need to go above 1.5v up to about 2133mhz. All I was getting at is that 1.65v shouldn't be needed until you reach the higher OC's. I was told by Ramguy the reason Intel doesn't list 1.65v in the white papers is because they don't cover memory overclocking. Those are specs for a CPU running bone stock.

 

The only exception to that is having to add to gain stability. There are many reasons why you may need to add to your DIMM voltage. Systems vary greatly believe it or not. That amount of memory, speed, your CPU, MB all have small variances that could cause the memory to need more voltage. I would rather add slightly more DIMM voltage than IMC off the bat because IMC will generate more heat than just DIMM.

 

Hooded, you know that you can't trust your BIOS 100% to be accurate when reporting voltages. So without having a way to actually measure what the memory is truly getting, it may not be getting it's full 1.5v.

 

In the end usually a person going for the really high OC's doesn't care about warranties anyway. I also just wanted to clear up that running 1.65v memory wouldn't void your warranty too. That myth really needs to be stomped out! :)

 

BTW, Have you seen where Intel is offering a one time replacement on the "k" CPU if you burn one up overclocking?

 

Sorry this got off topic a bit . I hope you enjoy your new build. :(

Thanks - all makes sense. Didn't know about the one time offer, very interesting! :)

 

Edit: Oh yes, I have the latest bios but it still doesn't offer .1v increments.

I thought you had to pay about $30 or something from intel for the overclocking warrantee ? Either way it's a good deal lol.