RAM compatibility

[Charlie Zulu]

Hi,
I know very little about OC’ing for the moment but, I at least need to ensure that my selections of self build components are compatible especially when I come to OC.
My choice to date is an i7-3930K and an ASUS P9X79 PRO.
http://www.ebuyer.com/288239-intel-core-i7-3930k-3-20ghz-socket-2011-12mb-cache-retail-boxed-processor-bx80619i73930k
http://www.ebuyer.com/291430-asus-p9x79-pro-socket-2011-8-channel-audio-atx-motherboard-p9x79-pro

I’ve found the following low CAS, 4 stick, RAM which is 1.6V. I think this may be too high?
http://www.amazon.co.uk/s/ref=nb_sb_noss?url=search-alias%3Daps&field-keywords=b0035xa9v4&x=7&y=22
but when I look at Intel for a guide to compatibility it refers to two voltages 1.35 and 1.5.
http://www.intel.com/support/motherboards/desktop/dx79si/sb/CS-032852.htm
I realise that this is their own MOB but for compatibility purposes, even though I don’t understand Voltage matters, I wonder if my choice of ram and its voltage will be in conflict with my choice of MOB and CPU?

Your advice would be appreciated.

 

[blazorthon]

Get 1.5v modules, if possible. Sandy Bridge can operate with higher/lower voltage modules, but 1.5v is recommended for a reason. Sandy is designed to be most stable with 1.5v and you are taking a risk to use higher voltages.

 

[Charlie Zulu]

Get 1.5v modules, if possible. Sandy Bridge can operate with higher/lower voltage modules, but 1.5v is recommended for a reason. Sandy is designed to be most stable with 1.5v and you are taking a risk to use higher voltages.

Thanks. That's just the info I'm looking for, although it makes the job of finding low volts,low cas more difficult this side of the pond.
Sorry for the delay in replying.

 

[abekl]

You want something with specs like the following:
http://www.amazon.co.uk/Corsair-CML8GX3M2A1600C9-Vengeance-1600MHz-Memory/dp/tech-data/B00569K7LM/ref=de_a_smtd

 

[Charlie Zulu]

You want something with specs like the following:
http://www.amazon.co.uk/Corsair-CML8GX3M2A1600C9-Vengeance-1600MHz-Memory/dp/tech-data/B00569K7LM/ref=de_a_smtd

Thanks.
The main use of my self build will be to run FSX and the advice from the FSX forums is that I should use low CAS 6 or 7 but it looks like I may have to compromise on low CAS in the interests of stability.

 

[blazorthon]

With that in mind, maybe you can overclock a 1.25/1.35/1.5v kit to about 1.6v, it should be fine on SB. Actually, SB is rated for up to something like 1.57v or 1.58v, I don't remember exactly where. If your motherboard supports voltage tuning that finely, then you could try for a lower CAS than otherwise. I just don't recommend stepping it up even close to 1.65v, try to keep it lower than 1.6v.

CAS, as in timings, is not as important as actual latency. Remember, a CAS of 7 @ 1333MHz is actually a slightly higher latency than a CAS of 8 @ 1600MHz (although it's very close). It's kinda misleading to say CAS without saying the frequency as well.

I've heard of MANY people that run their SB system with 1.65v memory without problems so far, but it seems to reduce the life time of the CPU considerably. Not too big of a deal for people who upgrade frequently (more than once every three years), but I like my machines built to last at least five years. I'm just getting around to replacing my 2007 desktop and my 2008 laptop.

G.Skill has a 1.25v RAM 1600MHz 9-9-9-24 kit. Overclocked to 1.5v, it should be able to handle significantly lower timings, or significantly higher frequencies at the same timings. G.Skill also has a 1866MHz 9-9-9- kit @ 9-9-9-24, maybe you can lower it's frequency to 1600MHz and increase the voltage to like 1.55v and get CAS 6 or 7 on it. I can't guess what you will manage with the 1.25v kit. Both are 2x4GB kits and here's the links if you want to look:

http://www.newegg.com/Product/Product.aspx?Item=N82E16820231461

http://www.newegg.com/Product/Product.aspx?Item=N82E16820231460

Honestly, if you want even lower latency, then your best option is probably to go for high frequency, low or moderate latency kits, and underclock them until you can get latencies that you consider tight enough.

Otherwise you'll find yourself needing to pay some fairly high prices to get a kit that has low latency at stock. Lower latencies can cost more than higher bandwidths that can be underclocked to get the same lower latencies.

 

[Charlie Zulu]

With that in mind, maybe you can overclock a 1.25/1.35/1.5v kit to about 1.6v, it should be fine on SB. Actually, SB is rated for up to something like 1.57v or 1.58v, I don't remember exactly where. If your motherboard supports voltage tuning that finely, then you could try for a lower CAS than otherwise. I just don't recommend stepping it up even close to 1.65v, try to keep it lower than 1.6v.

CAS, as in timings, is not as important as actual latency. Remember, a CAS of 7 @ 1333MHz is actually a slightly higher latency than a CAS of 8 @ 1600MHz (although it's very close). It's kinda misleading to say CAS without saying the frequency as well.

I've heard of MANY people that run their SB system with 1.65v memory without problems so far, but it seems to reduce the life time of the CPU considerably. Not too big of a deal for people who upgrade frequently (more than once every three years), but I like my machines built to last at least five years. I'm just getting around to replacing my 2007 desktop and my 2008 laptop.

G.Skill has a 1.25v RAM 1600MHz 9-9-9-24 kit. Overclocked to 1.5v, it should be able to handle significantly lower timings, or significantly higher frequencies at the same timings. G.Skill also has a 1866MHz 9-9-9- kit @ 9-9-9-24, maybe you can lower it's frequency to 1600MHz and increase the voltage to like 1.55v and get CAS 6 or 7 on it. I can't guess what you will manage with the 1.25v kit. Both are 2x4GB kits and here's the links if you want to look:

http://www.newegg.com/Product/Product.aspx?Item=N82E16820231461

http://www.newegg.com/Product/Product.aspx?Item=N82E16820231460

Honestly, if you want even lower latency, then your best option is probably to go for high frequency, low or moderate latency kits, and underclock them until you can get latencies that you consider tight enough.

Otherwise you'll find yourself needing to pay some fairly high prices to get a kit that has low latency at stock. Lower latencies can cost more than higher bandwidths that can be underclocked to get the same lower latencies.

Thanks for the detail.
I am learning to understand the interaction between components but as yet, have no experience of OC’ing, so very much feeling my way. Just choosing components at the moment.
Your comments open up a much wider view to research.

 

[blazorthon]

Glad I could help. I'll try to answer any other questions you might have.