XPS 720 Memory upgrade issue

Question

OK, I have an XPS 720 with two 1 gig memory chips. First off when I go to the online system configuration for my service tag, it gives no usable information on the memory that was installed . I pulled the chips and they are Corsair Dominators but there of course is no part number. I lookup what the online system upgrade configurator recommends for my service tag and it tells me to use the Corsair TWIN2X4096-6400C5DHX but something seems wrong, so I call Corsair. They tell me that Dell ordered the chips with no identifiable part number by design but to use CPU-Z to get the part number form the chip. Low and behold they are not what Dell says but in fact they are CM2X1024-8500C5D chips which is what I thought (1066 Mhz not 800 Mhz which is what dell wanted to sell me to upgrade). I call Corsair back and they tell me that the system may not function if I add the 2 gig chips (TWIN2X4096-8500C5D) with the 1 gig chips that are in the system (TWIN2X2048-8500C5D or CM2X2048-8500C5D0 – kit part / chip part). They think I need to go either 4 x 1 gig chips or pull the 1 gigs and put in 2 x 2 gig chips. This is a 64 bit system running Windows 7 64bit. OF COURSE THE MANUAL SAYS NOTHING!!!

Does anyone have any ideas???

osprey4 · Answer

Hi, Raidernick: You mean this section of the manual? Looks like all the information you need to me. Anyway, here's what Crucial says. Guaranteed compatibility.

Davet50 · Answer

I'm running 8 gigs of OCZ reapers at 800mhz in my system. Before that i had 4 gigs of OCZ reapers installed.

Now the 720 is very picky about the memory. The biggest factor one must look at is the voltage requirements for the sticks. You should keep the voltage requirements to 2.0v or under.

raidernick · Answer

Really. Where in that section, which according to you has all the information, does it say that the system supports 1066 Mhz memory or what the memory voltage requirement is? Where does it say 1x1024 pairs can or cannot be used with 2x2048 pairs. Even Corsair says that matching the voltage is critical between pairs or the memory will be unstable.

And your Crucial memory is not compatible. The only 2x2048 1066Khz is a 1.8 volt module where the Corsair sold with the XPS are 2.1 volt.

Davet50 · Answer

The system will support 400,800 or 1066 memory. You can go with 1 gig per slot or 2 gig per slot.

The voltage requirements are something that us 720 owners have discovered. You will get away with the 2.1 volt sticks if you only use 2 slots. If you want to populate all four slots then you must keep the voltage on the sticks to less than 2.1. The memory controller on these boards is very finicky about voltage applied to the sticks when using all four slots..

raidernick · Answer

Thank you.  This is what I was looking for, an educated answer.

Davet50 · Answer

Your welcome. comes more from personal experience and lots of reading...

rdunseith · Answer

@Davet50 Just curious if this is the ram your using, http://www.ocztechnology.com/products/memory/ocz_ddr2_pc2_6400_reaper_hpc_4gb_edition ? Thanks, Robert

Davet50 · Answer

That's them .

raidernick · Answer

NO, I'm using the CM2X1024-8500C5D and will be switching to the CM2X2048-8500C5D so that I can get 4 Gb in the system. For any of you who are curious I finally got aa straight answer from Corsair which explains why Dell does not have 1066 memory listed as a system upgrade for the XPS 720.  The XPS 720 will only run 1066Mhz 2.1v memory stably in 2 slots (whether it be 1 gig or 2 gig chips).  It cannot handle four slots of memory at that speed.  You can clock them down but then what would be the point.

Mr. Naculation · Answer

Hi.

I'am new in this community and my English ist not very very good.

I have the XPS 720 H2C System with actually 2x 2GB (originally shipped with my pc). Now I'm very interested to upgrade and use all 4 banks. I will use 8GB naturally with a 64 Bit system.

I have read a lot but I'm always not shure what I shoud do. I'm interested to by this modules Corsair TWIN2X4096-8500C5D but it seems that they will not go to work in this pc. Dell also said to me, that only 2x 2GB of this rams will work best, for 4x 2GB I have to try at my own risk.

Can you please help me??

Davet50 · Answer

I don't know of anyone who has had success with 1066 memory at 8 gigs. I honestly do not feel the system will handle it.

Davet50 · Answer

I am running 8 gigs of THESE

Mr. Naculation · Answer

Ok, I know, that's fine. But I mean 8GB (4x 2GB) with 1066MHz not 800MHz.

Mr. Naculation · Answer

hmm, ok. Perhaps this can help you, because I havent really the same system components like you:

As I mentioned I have the XPS 720 H2C with:

Intel Core 2 Extreme QX6850 FSB 1333MHz

with the nforce 680i SLI mainboard

and dual nvidia geforce 8800 GTX SLI

bios is already updated to A06

have I a chance?

Davet50 · Answer

You have the same exact motherboard. the H2C is only liquid cooling as you have QX6850 processor.

Techinally and specs wise our systems are the same.

Like I have come to find the motherboard is very very picky about the ram you use especially when you populate all 4 slots. The memory controler on these boards is not that robust and therefore will either 1. downclock the ram or 2. refuse to boot.

for 4 gigs the system will handle the 1066 memory. anything over that gives the controller fits.

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XPS 720 Memory upgrade issue

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