RAM compatibility question

[Creamy_Goodness]

Hi guys,

In the process of building an i5 750, and with the limited choice at my disposal in ZA, have chosen an Asus p55 LE board(not purchased yet).

Problem is that choices of RAM are fairly limited when trying to stick to the Asus QVL. I was going to go with the Corsair TW3X4G1333C9DHX G, but according to the Asus list, this ram cannot run in Dual Channel mode, even though it is 2*2gig package.

The following taken directly from their QVL:
Supports two (2) modules inserted into the blue slots (A1 and B1) as one pair of Dual-channel memory configuration.

(This option is not ticked off on their QVL for the ram in question)

Am I misreading this? I thought the fact that it is sold as a matching pair of modules implied dual channel usage, or is this perhaps an omission / error on their QVL?

Thanks for any insight you can provide...

 

[dividebyzero]

You're reading it right. The Asus QVL has qualified the RAM to run as one module in one DIMM.
The problem with a lot of manufacturers is that they rush the boards in the retail channel before the RAM kits have been produced (hence a lot of P55 chipset boards have a lot of tri-channel (X58) kits on their QVL's) and the compatible memory list is never upated to include newly released RAM as they are released. Asus normally only updates their QVL when the board's BIOS is upgraded to run higher bandwidth memory.
The memory configurators of the RAM manufacturers is more of a useful guide.
http://www.corsair.com/configurator/default.aspx
As you can from the given selection here...
http://www.corsair.com/configurator/product_results.aspx?id=1106001#other_modules
The module kit Asus have qualified does not appear on their list-this is because, as you say, the modules are designed to run in dual-channel mode. You may also note that Asus have qualified modules running at 1.7-2.0v when Intels i3/-5/-7 CPU specification notes the running RAM at voltages exceeding 1.65v can damage the on-die memory controller.

As an aside, the RAM you've mentioned isn't particularly great. Unless you're getting it very much cheaper than retail I would consider it an average-to-poor buy. You are in effect paying premium rate for average memory chips stuck under a fancy Dominator branded heatspreader. The XMS branded Corsair RAM is exactly the same as the Dominator at 1066/1333/1600 and cheaper-it just looks a little plainer.
G.Skill RAM if available to you would probably offer better functionality, although you may need to manually set the timings and voltage in the BIOS (a 5 minute exercise at most)
http://www.gskill.com/configurator2.php?pid=2&model=969
Crucial's RAM is more expensive generally but is excellent memory
http://www.crucial.com/store/listparts.aspx?model=P7P55D LE
Kingston are the benchmark for many motherboard qualification tests
http://www.ec.kingston.com/ecom/con...D+LE+Motherboard&distributor=0&submit1=Search
OCZ
http://www.ocztechnology.com/ > Tools > Configurator

If the memory is stated to be XMP then the RAM has an embedded XMP profile that your motherboard can read and automatically set default timings and voltages.


As a side note you may well have a post on this thread from some "supposed" experts telling you that you should never ever deviate from the manufacturers QVL.
Should that be the case then you can take their information to heart, ot you could ask them if they are prepared to underwrite the cost of a new CPU if the memory controller blows because you attempted to run the RAM at it's rated bandwidth that required 1.8, 1.9 or 2.0 volts

 

[Creamy_Goodness]

Thanks so much for your insight - I will check out the configurators on the various websites. Unfortunately G.Skill and Crucial are not available here but Kingston and OCZ are.

Funny enough, I was looking at the OCZ gold edition OCZ3G13334GK which, after now checking their configurator is compatible, but in their specs it's rated at 1.7v, while Kingston's KVR1333D3N9K2/4G is rated at 1.5v

At that voltage, how/why do you think OCZ can recommend this? An error on their part or is 1.7v close enough to the threshold. I must admit, I am leaning towards the Kingston now.

Thanks again.

 

[dividebyzero]

That's a screw-up on their page- it's linking to the kit meant for LGA775 motherboards. Good catch that you noticed the operating voltage was too high.
Here is the correct kit: OCZ3G1333LV4GK

http://www.ocztechnology.com/products/memory/ocz_ddr3_pc3_10666_gold_low_voltage_dual_channel
Note the LV it denotes Low Voltage- You'll see that it is 1.65v
Either this kit or the Kingston will be fine. OCZ's return policy should you ever have problems with it is an easier process. Both kits have lifetime warranty's.

 

[Creamy_Goodness]

Excellent, thanks for that. I will double check that the part number is correct before delivery. The Kingston would be my first choice, just because of the 1.5 voltage, but if ocz has a better returns policy then I'll be happy with that too just in case I have problems down the road.
The only other mainstream ram I can easily get my hands on is Patriot, and I've had issues with their ddr2-800 in the past so not too confident with them.

Problem here is that the 775 is still used in the majority of systems, and as such most suppliers hold ram for these, so low voltage ram is really slim pickings.

Thanks for your help!