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Memory compatibility confusion

Last response: in Memory
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April 18, 2010 9:58:07 AM

Hello,

I'm planning to build a desktop, however, I'm confused about what RAM is compatible with the motherboard. I have been searching for quite a while.

The motherboard would be Gigabyte's GA-P55-USB3 (rev. 1.0). From specifications:

1. 4 x 1.5V DDR3 DIMM sockets supporting up to 16 GB of system memory
2. Dual channel memory architecture
3. Support for DDR3 2200/1333/1066/800 MHz memory modules
4. Support for non-ECC memory modules
5. Support for Extreme Memory Profile (XMP) memory modules

The ram I was going to use was:
OCZ Obsidian Triple Channel PC geheugen 3 x 2 Gb DDR3-1600 PC3-12800 (OCZ3OB1600LV6GK)
From specifications (not sure if these are correct..there are 3 very similar products on the site):

1600MHz DDR3
CL 9-9-9-24 (CAS-TRCD-TRP-TRAS)
Available 6GB Triple Channel Kits
Core i7 Ready
Unbuffered
Obsidian Black XTC Heatspreader*
Lifetime Warranty
1.65 Volts
240 Pin DIMM

I have four questions:

1) I've noticed the motherboard states 1.5V DDR3, whereas the RAM is 1.65V. Is this a problem? I seem to be unable to find RAM with a voltage of 1.5.

2) This RAM memory does not appear in the 'compatible memory list' of the motherboard. This list does state that a lot of RAM is not tested, since there is a huge amount of them.. should I be worried by it not being in the list?

3) Is this RAM compatible?

4) Will inserting 3chips of 2GB in a dual-channel system just be suboptimal, or would my system not recognize the third chip?

Any help will be appreciated.
Thanks
a b } Memory
April 18, 2010 12:18:10 PM

1) No, I'm supposing it's only officially meant to run at 1.5V, but can easily run at 1.65V. RAM at stock always runs at 1.5V regardless.

2) No, the memory list can't cover everything, and my memory modules weren't on the QVL on EVGA's website, but it booted perfectly.

3) Probably, don't see why it wouldn't be.

4) Three sticks of 2GB in a dual channel system will mean you will be running 6GB of RAM in single channel.

Note that you need a dual channel 4GB or 8GB memory kit for LGA 1156 motherboards, which is one you have. If you really want to play it safe - get a DDR3 Corsair Dominator or XMS3 RAM kits, which are generally compatible/designed for P55 motherboards.
April 18, 2010 2:06:48 PM

Lmeow said:
...
4) Three sticks of 2GB in a dual channel system will mean you will be running 6GB of RAM in single channel.

Note that you need a dual channel 4GB or 8GB memory kit for LGA 1156 motherboards, which is one you have. If you really want to play it safe - get a DDR3 Corsair Dominator or XMS3 RAM kits, which are generally compatible/designed for P55 motherboards.


A dual/triple channel kit does have two/three identical sticks, right? Or do the sticks in a dual channel set differ for the dual channel functionality? I thought this was all motherboard-functionality..

thanks
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April 18, 2010 6:24:37 PM

To run in dual channel the number of sticks needs to be a multiple of 2. You have 3 sticks of ram which means you can't run in dual channel. It's not about the sticks.
April 18, 2010 7:36:02 PM

In answer to your other question about the kits. It is mainly a marketing thing. I have used single sticks and they ran in dual channel just fine. In fact I have ran single sticks of different brands with the same specs and had no problems. If you buy the better brands like OCZ, Corsair, Crucial, and Mushkin, you shouldn't have any problems.
a b } Memory
April 18, 2010 7:49:36 PM

Sir G said:

1) I've noticed the motherboard states 1.5V DDR3, whereas the RAM is 1.65V. Is this a problem? I seem to be unable to find RAM with a voltage of 1.5.

2) This RAM memory does not appear in the 'compatible memory list' of the motherboard. This list does state that a lot of RAM is not tested, since there is a huge amount of them.. should I be worried by it not being in the list?

3) Is this RAM compatible?

4) Will inserting 3chips of 2GB in a dual-channel system just be suboptimal, or would my system not recognize the third chip?


1. it will work but you should get the proper mem the reason it only lists to 1.5 volts is because mem controllers for i5 and i7 chips is in the cpu not on the mb
you didn't look very hard here's several at the same speed but the right voltage
http://www.newegg.com/Product/ProductList.aspx?Submit=E...
your board also dosn't support 1600 though once again you should be able to make it work here is some ram your mb does support
http://www.newegg.com/Product/ProductList.aspx?Submit=P...

2. don't worry about the QVL list as long as the specs match

3. it'll most likely work, it's the wrong voltage and speed though

4. the mb will see the all three chip but it will run in single channel, with that mb you should either get two or four chips so you can take advantage of the dual channel
April 19, 2010 3:48:53 PM

I did not look on newegg (which is a very handy and organized site, thanks!) because I did not want to ship the components from foreign countries. It's pretty hard to find 1.5V ram from more local sources. However, I recently have found a 4GB kit of ocz golds low voltage, and 8GB (4x2gb) dual channel kit of 1.5V 1333mhz from Corsair. This second kit is probably overkill, oh well..

I asked the information for the 1600mhz stick because I found a lot of ambiguous information. The motherboard states it indeed does not support this speed, however 1600mhz chips are listed in the QVL, and vendor sites like ocz and corsair both include 1600mhz chips in their list of compatible ram. I'm guessing they'll just work at a lower compatible speed (1333mhz)..

a last question: in general (so not referring to the kits i just mentioned) what are the pros and cons of low voltage ram? From what I understand they'll both work, yet the Low Voltage RAM would be more 'overclock-capable'. I do not intend to overclock, so should I avoid low voltage, or doesn't it have any cons over 'normal voltage' ram?
a b } Memory
April 19, 2010 3:59:48 PM

there is no con to low voltage ram, it just requires less power which reduce stress on your other components (mainly the mem controller which in your case is in the cpu), saves power, and generates less heat
the reason there is higher voltage rams is because cheaper chips require more power to do the same thing, it's a quality issue

ram is always hard to source form stores, it's just not practical to stock a huge variety in a storefront location

yes the 1600 will run at a lower speed but it will also run at a higher cas than lower speed ram, unless you know how to manually set it which can be tricky at times.

If you are just going to put it together and run it then get the exact specs otherwise you will be wasting money and performance
April 20, 2010 7:31:13 AM

alright. Thank you for all your help :) 
a b } Memory
April 20, 2010 12:34:27 PM

glad to help
!