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Asus p7p55d-e lx - can I use 3 memory sticks 3x4GB for 12GB of RAM?

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February 12, 2011 7:21:10 PM

I am planning a new build with an ASUS P7P55D-LX mobo and a core i7-870. The motherboard does not support triple channel RAM, but has 4 slots and the specifications say that it will support a maximum of 16GB of memory.

My question is, can I populate 3 of the 4 slots with 4gb sticks and have the system recognize a total 12GB of memory? The memory kit I'm looking at is a GSKILL F3-10666-12GBR (http://www.newegg.com/Product/Product.aspx?Item=N82E168...)

Thanks!

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a c 347 } Memory
a c 207 Ĉ ASUS
February 12, 2011 8:06:43 PM

Welcome to Tom's Forum! :) 

The best answer is 'maybe', unlike 3X2GB kits e.g. F3-10666CL9T-6GBNQ that are on the QVL list 4GB sticks are often BIOS version dependent so they will work. Therefore, if it were 'me' start a ticket with G.SKILL to confirm -> http://gskill.com/contactus.php

Installing 'odd' sticks in otherwise Dual/'Quad' configurations breaks the Dual Channel mode.

Normally, you don't need more that 4GB Dual Channel/6 GB Tri Channel in a 64-bit OS, and clearly your OS must be a 64-bit OS to use >4GB of RAM. Home Premium 64-bit is limited to 16GB; Win 7 Basic 8GB. http://msdn.microsoft.com/en-us/library/aa366778(v=vs.85).aspx

That said, if it were 'me' the following Tested Dual Channel Kits:
G.SKILL Ripjaws Series 16GB (4 x 4GB) DDR3 1333 F3-10666CL9Q-16GBRL http://www.newegg.com/Product/Product.aspx?Item=N82E168...
G.SKILL Ripjaws Series 8GB (2 x 4GB) DDR3 1333 F3-10666CL9D-8GBRL http://www.newegg.com/Product/Product.aspx?Item=N82E168...
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February 12, 2011 8:17:43 PM

Thank you for the welcome and the response. I've been doing some more reading since I posted, and I found a couple of people using similar configurations who reported that only 8GB was visible. I also looked at the manual, and it does not say that using 3 sticks is a valid configuration.

Yes, I will be using a 64 bit OS, and extensive virtualization, so 12GB is a minimum for what I need. I think this might be the impetus for me to switch to a 1366 board with triple channel support. I can get an ASRock x58 board for a little more than what I paid for the ASUS board and I will get my 12GB without having to fill up all the RAM slots.

Thanks again for the response!
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February 12, 2011 8:18:05 PM

Best answer selected by bigbluebeetle.
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a c 80 } Memory
a b Ĉ ASUS
February 12, 2011 8:43:16 PM

They might work, but I suggest that you buy modules on the QVL if you want to use that much RAM. Instead of a triple channel kit, why not buy a kit that's on the list for the Asus P7P55D-E motherboards at gskill.com?

F3-8500CL7Q-16GBRL (4Gx4)
F3-10666CL9Q-16GBRL (4Gx4) - Read the note which basically means that they'll run at 1066 instead of 1333 when using 4 modules.

EDIT: jaquith beat me to it.
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February 14, 2011 7:58:42 PM

I suppose I could just get the 4Gx4 kit, but that would involve:

a. Spending more than I would for 12GB (and not being able to run the RAM at 1600MHz)
b. Filling up all the memory slots, which may cause heat issues if I decide to overclock

Is that accurate? That's what I came up with after a few days of research.

Since I already ordered everything other than the processor, I might just try the 12GB to see if it will work, and then just go down to 8GB if it doesn't, and add another 8GB later (when I can afford it!).

What are the performance differences between RAM running at 1066 MHz vs 1600 MHz in real-world usage? As I said earlier, the primary uses will be to run multiple VMs and play a few games. I understand there isn't much difference between single-channel vs dual-channel (5-7%), but does the speed make a bigger difference?
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a c 347 } Memory
a c 207 Ĉ ASUS
February 14, 2011 8:22:23 PM

I'm a little foggy, above was discussion about both the P55 and X58. Sooo what did you decide upon?

The 1333 vs 1600 MHz question - ANS if I needed >GB with <$ then the 1333 MHz wins, if money isn't a big concern and you're running either an i5 or i7 then sure the 1600MHz. The difference depend upon the RAM, can be anything from the 1333 MHz outperforming the 1600 MHz to best case 2~8FPS. There too is a gain in 64-bit with 8GB vs 4GB http://www.tomshardware.com/reviews/ram-memory-upgrade,...

The real differences are Frequency :: CAS and Quality of the IC. Example, 1600 9-9-9-24 can run 'close' to the same performance running 1066 7-7-7-20. The Frequency alone adds in a typical Game 2~4FPS with using the SAME IC. The Dual vs non-Dual Channel can be more dramatic in operations requiring full bandwidth.

90% is the IC use in the RAM.

IF you get 2X2GB + ODD 4GB then that's it. Chances are the 'ODD' 4GB will never run properly even if the SAME 'ODD 4GB' is added later - reason it's not a BIN sorted matched Kit. It's like rolling the dice.
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a c 80 } Memory
a b Ĉ ASUS
February 14, 2011 11:17:05 PM

Quote:
As I said earlier, the primary uses will be to run multiple VMs and play a few games.
When running several VMs, the hard disk(s) will probably be the bottleneck.
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