We have a T5400 with 18 Gb Ram installed 4 4Gb sticks and 2 1 Gb sticks The BIOS reads 10 Gb but shows all sticks installed Anyone have any idea what i need to do all Mhz on all sticks are 667 Learning in progress..........

I don't know of any mboard in which you can install 18gb of ram. If you can install two types of ram, the mboard recognizes only one of the two types at a time. Go to a ram manufacturer's web site and look up which sizes of modules you can install in your brand and model. e.g. www.kingston.com www.crucial.com www.corsair.com

Well it has 8 slots so i would imagine it is built to hold this amount + more Also it is 64 bit so it can support more ram than 32 bit Learning in progress..........

The dell T5400 workstation is capable of handleing up to 32 gigs of ram. The ram must be ECC and that might be your problem. Check each ram stick and verify it is ECC vs. non ECC. If it is Non ECC (Error correcting) then the system will recognize that the ram is installed but will not be ablwe to us eit as it is the wrong type. It is the disadvantaged who habitually elect Democrats on the belief of personal change--- yet they remain disadvantaged.

It does not matter to the bios whether your operating system is 32 or 64 bit. You specified your model as T5400. I assume it's a Dell Precision Workstation T5400 "Quad-Channel Full Buffered DIMM ECC Memory Speed 667MHz fully buffered DIMM ECC Maximum Memory 32GB (4GB ECC DIMMS x 8 slots)" ..... Examples of ram modules compatible with your model: http://www.ec.kingston.com/ecom/con... This says the ram must be installed in matched pairs. http://www.crucial.com/store/listpa... ..... Your problem is probably that some ram modules you have installed are not compatible with the mboard chipset, or if your mboard and cpu are recent enough, some of the ram you have installed is not compatible with the memory controller that is built into the cpu. Ram that works in another mboard , or any ram you buy or have lying around, may not work properly, or sometimes, not at all - even if it physically fits and is the right overall type (e.g. SDram, DDR, DDR2, etc.; PCxxxx, xxx mhz) for your mboard. In the worst cases of incompatibilty your mboard WILL NOT BOOT with it installed, and the mboard may not even beep - the ram has to be compatible with the mboard and it's chipset. See response 5 in this for some info about ram compatibilty, and some places where you can find out what will work in your mboard for sure: http://www.computing.net/hardware/w... Correction to that: Mushkin www.mushkin.com Once you know which module ID strings work in your mboard, you can get them from anywhere you like that has ram with those ID strings. If you have brand name ram, it is usually easy to look up whether it's ID string is in a list of compatible modules found by using your mboard or brand name system model number. If the ram is generic, that may be difficult or impossible. ...... Installing more ram than you need is a waste of money - after a certain point adding more WILL NOT make your system perform better. Ultimate Memory Guide How Much Memory Do You Need? etc. http://www.kingston.com/tools/umg/u...

We found the problem we needed to add the ram in matched pairs and put the lowest ram (Eg. 1 Gb compared to 4 Gb) first thank you for the response much appreciated Learning in progress..........

Usually if you can install ECC ram, you can also install non-ECC ram as well, but it has been recommended for a long time that you install ECC ram rather than non-ECC ram,if you can, if you have more than 512mb of ram installed.