Memory limits help

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Please move if I'm totally in the wrong place!


A buddy has a Dell Inc. Dell XPS72 (This is a 32 bit system but i'm about to upgrade to 64bit), when I got to it and checked it's memory it has the following:
Slot 'DIMM_1' is Empty
Slot 'DIMM_3' has 256 MB (serial number 00005200)
Slot 'DIMM_2' is Empty
Slot 'DIMM_4' has 2048 MB (serial number 929AC451)



This really surprised me. A 265MB card? In the bios it said that it was at x16 speed as opposed to the other card being a x1 speed. I didn't really understand that.

So I went away and got matching 2GB ram
4GB kit (2x2GB) DDR2-1066 CL7 NonECC PC2-8500

Put it in, took out the 256MB, and it didn't boot. Didn't have time to fiddle about with it so I just put back in the 265mb and she booted. The BIOS and vista recognised everything, all good.....

I help this buddy one out remotely so I was back in yesterday because of some outlook config problem and I was surprised how slow the system was with all that memory. I know it won't see all 6.25 GB but it should at least see the 4gb, right?

In Windows Experience rating thing it shows the 6.25 gb, but in task manager it only has physical memory at ~2033 MB.
Shared System Memory is at about 756MB (or something like that, from the details of teh win experience screen under graphics).

Anyone got an idea why Vista is only seeing about 2GB of my 6.25 GB? I'm about to upgrade to Win& 64 Bit but don't want any memory or hardware issue to carry over to the upgrade as the system is working currently.

I'm not in front of the PC but i am remotely connected, as soon as I get out to it I will play around with different slots full, empty etc...
But in the mean time any one knows why I only got 2GB in task manager?


Dell XPS72 with Windows Vista Ultimate Service Pack 2 (build 6002) 32 bit but about to upgrade to 64 bit:
Slot 'DIMM_1' is 2048MB
Slot 'DIMM_3' has 256 MB
Slot 'DIMM_2' is 2048MB
Slot 'DIMM_4' has 2048 MB
Windows Experience rating seeing 6.25, Task manager only seeing 2GB roughly. I was expecting something closer to 4GB (3.7GB), any ideas?

I've done a lot of different stuff but I'm willing to start again and go through all the basic steps.
Thanks for reading,
Derry

Hi, my understanding on RAM was they are to be matching pairs.

That was my understanding as well, but someone at some stage. (Only dell have hand there hands on this box before me). Put in 2GB plus 265mb (fiddles with BIOS) and then teh system accepted the 256 with the 2gb, It works.

The problem is now going to upgrade to 64 bit and adding ram, I'm concerned that there may be something in the BIOS that need to modify to get a clean list of ram.

Thanks for the quick reply.
Derry

Here is a speccy read out of mine. Memory
Type DDR2
Size 2048 MBytes
Channels # Dual
DRAM Frequency 387.5 MHz
CAS# Latency (CL) 6 clocks
RAS# to CAS# Delay (tRCD) 6 clocks
RAS# Precharge (tRP) 6 clocks
Cycle Time (tRAS) 18 clocks
Bank Cycle Time (tRC) 25 clocks
Command Rate (CR) 2T

I got my info. from speccy.com for my hardware. Which shows motherboard and etc, The thing about BIOS settings is what is confusing me. Maybe someone else has some ideas on that, as there are a bunch of very knowledgeable people at this forum. So, hang loose for one of them to give you more assistance.

Thanks for that, I'm hoping to find an active Dell forum some where as well.

Ta,
Derry

hey, me again, Can you explain the Bios thing you " fiddled " with, i just went into my Bios settings and i see nothing there to duplicate this setting you seem to have adjusted .

Hello Derry, and welcome to Vista Forums.

The problem is that since this is DDR2 RAM, you will need to have matching pairs to be able to run them in the faster "dual channel" mode. The way you have it set now, it will only run in "single channel" mode.

To have the best performance, try having only the newer matching 4GB kit (2x2GB) DDR2-1066 CL7 NonECC PC2-8500 RAM in slot 1 and 2 like below. Slots 1 & 2 should be the same color, and 3 & 4 should be the same as well but different color than 1 & 2. If it doesn't work with them in slot 1 & 2, then try then in only slot 3 & 4.

Slot 'DIMM_1' is 2048MB
Slot 'DIMM_3' empty
Slot 'DIMM_2' is 2048MB
Slot 'DIMM_4' empty

Since the older pair are not matching, you will need to leave them out.

Double check your BIOS settings to make sure that the new pair are running in dual channel mode.

Hope this helps,
Shawn

Thanks for all your replies,

I'll definitely being going down the road as per @brinik. rip out that old memory set up and go with just the 4 gb.

A question on the Dell XPS can I leave in the extra 2gb or do you have to have matching pairs?

Whats the story there have not been able to find something specific telling me what will happen if i put in the extra 2gb?

Once i get in front of this machine I will make the changes, and report back on what exactly the BIOS says.

Thanks again,
Derry

You have to have matching speed, pairs , etc. they have to match.

Welcome
If you do not feel comfortable picking out the correct ram, this site will help
RAM Memory Upgrade: Dell, Mac, Apple, HP, Compaq. USB drives, SSD at Crucial.com

Thanks lads,
I am totally confy picking out RAM.

@Brink I just re-read your post and I totally missed the part about DDR2 as in dual!!!

Thanks for that so if I add in the extra 2GB it will just run at single channel.

So this system has 6.25 GB of ram:
Slot 'DIMM_1' is 2048MB
Slot 'DIMM_3' has 256 MB
Slot 'DIMM_2' is 2048MB
Slot 'DIMM_4' has 2048 MB

But task manager is only seeing 2044 BM, just checked again.

Can anyone tell why this would be?
P.S. Yard Dog, as per my post i didn't fiddle with anything in the BIOS. But when I get at the box again I'll report back on what was actually done with the 256 of ram in the bios.

Ta,
Derry

Derry,

With DDR2 RAM, you need to use matching pairs of RAM module sticks for them to be able run in "Dual Channel" mode. If you do not have matching pairs, or add the other ones that do not match, then the RAM will only run in "Single Channel" mode and default to the speed (MHz) of the slowest RAM module installed. In other words, you would drastically hurt the performance of the RAM if you do not use matching pairs of RAM sticks.