How much memory

Mercedes-Ben

Mercedes-Ben

Mercedes-Ben

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Joined
11 Sep 2008
Posts
18
I have an ASUS P5Q deluxe mobo, with XP PRO 32.
I had 2x1gig Corsair Dom. 8500 (1066) and installed another 2gig of the same (4 gig in total) My pc would not boot till I removed one of the sticks (both are serviceable). My pc shows 3 gig ok. Can I tweak something to show 3.5 gig?

pc probe shows current speed of 19ns on all 3 sticks

thanks
 
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how much ram does your graphics card have? as this is also taken into consideration for the 4gb so if you have a 1gb of gddr then 3gb is right.
 
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The problem with running with 3 sticks is that you will be in single channel mode. The memory limit of a 32bit OS will be nothing to do with why the PC wont startup. Try increasing the the northbridge voltage slightly
 
Thanks, I tried booting 3 times with four sticks, and it wont boot. It boots fine with three though ?? If I increase the northbridge voltage will it run in dual channel mode, and perhaps show 3.5 gig of memory ? Please excuse my ignorance, but where exactly in the bios of my P5Q deluxe mobo will I find the northbridge voltage, and by how much should I increase it?

I found this here http://www.overclockersclub.com/reviews/asus_p5q_deluxe/5.htm which looks like my answer I think?? Any suggestions ?

thanks for the reply sir.
 
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Dual channel is just when memory sticks work in pairs to run a bit faster so either 2 or 4 sticks. 3 sticks forces it back to single channel mode. Put 2 sticks in, increase northbridge voltage, save, shutdown. Try 4 sticks. Also make sure you have the correct VDIMM for the memory you are using.
 
I increased nb voltage to 1.76 and 4 sticks boot ok :D

The memory is now showing 3.25 gig with 4 sticks. Does this mean it is running in 2 channels ?
What is the vdimm sir? I found this .......So, for example, if you have a DDR2 PC2-8500 4gb kit, the chances are it will require 2.1v VDIMM. Now, in the VDIMM setting of the BIOS, change this to the new setting. Depending on your motherboard, this will either show as the actual voltage, or will show as +0.3v (increasing the default voltage by 0.3 to 2.1v). Once this is done, you can then save and exit the BIOS, then power down the PC and install the new RAM.

Once this is done, your new RAM will work as intended, and at the speed and timings it is rated for.



many thanks for your patience and help. Looks like a result :D as they say in football :)
 
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if you run cpu-z it tell you if you are running in single or dual channel. VDIMM is memory volatge. The default DDR2 voltage is 1.8v. BUT most memory kits might be rated at (E.G.) 2.1v 5-5-5-12 but will have a fail-safe 1.8v mode mainly for motherboards with no such options so might run at 1.8v 5-6-6-15 (again just an example). It's best to set everything to the memory's rated settings.

The 3.25 gig limit you are seeing is down to using a 32bit OS and nothing else at all.
 
It is showing dual channel sir, and DC mode symmetric :confused:Memory is 4x1gig Corsair Dom. 8500 (1066)

Many thanks

Is there anything else I should do, all seems ok.

thanks
 
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only set the VDIMM to the memory's specs. it's nothing to so with the motherboard. The motherboard will just do as it's told I.E pump whatever voltage into memory that you tell it to and it will just presume that's ok because you told it to !

is this your memory?? if so it seems to requite 2.1-2.3v to run at it's rated timings
 
Well you could stop there but the final thing i would do is run cpu-z and see what memory timings your motherboard has decided for you. See if they are the same as the advertised specs. **don't confuse this with SPD ** the SPD table it pretty much just text built into the RAM for yours and the computers reference of what it should be able to run. It's doesnt in any way represent what it is currently running at. Your RAM should be running at 5-5-5-15. These are the only 4 numbers worth bothering about really, the first "5" being the most important.
 
This is the text

Memory SPD
------------------------------------------------------------------------------

DIMM #1

General
Memory type DDR2
Module format Regular UDIMM
Manufacturer (ID) Corsair (7F7F9E0000000000)
Size 1024 MBytes
Max bandwidth PC2-6400 (400 MHz)
Part number CM2X1024-8500C5D

Attributes
Number of banks 1
Data width 64 bits
Correction None
Nominal Voltage 1.80 Volts
EPP yes (1 profiles)
XMP no

Timings table
Frequency (MHz) 270 400
CAS# 4.0 5.0
RAS# to CAS# delay 4 5
RAS# Precharge 4 5
TRAS 13 18
TRC 16 23

EPP profile 1 (full)
Voltage level 2.100 Volts
Address Command Rate 2T
Cycle time 1.875 ns (533.3 MHz)
tCL 5.0 clocks
tRCD 5 clocks (9.25 ns)
tRP 5 clocks (9.25 ns)
tRAS 15 clocks (28.00 ns)
tRC 22 clocks (41.00 ns)
tWR 8 clocks (15.00 ns)
 
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