ECC RAM. Can I combine kits ? Is it worth it?

[malcolm-hk]

I have an old Dell Precision T5400 workstation:
- 2xquad core Xeon CPUs,
- Windows 7 Pro 64Bit
- 4GB (2x2GB) FB-DDR2 ECC RAM

There are 8 memory slots on the motherboard. I've ordered a 16GB certified RAM kit on ebay (4x 4GB)

I want to use it to run 2 or 3 virtual machines: A small web server, an XP machine for some legacy software and from time to time a test machine. Nothing really intensive - but it would be good to have them all quick and responsive. I'll assign 2 or possibly 4GB to each VM. There may also be a need to work at the workstation from time to time...

Then yesterday I was offered another 16GB kit (2x 8GB) by the place I bought the machine. So now I have 3 Ram kits available - all tested on this model of workstation.

My question - if I can get 2 (or even all 3!) kits of RAM to play together will I see any benefit?
If I've got 6 or 8GB assigned to the VMs there should be enough left for the machine to be used.

Is it likely the 2x8GB kit will work with the 4x4GB? . I believe they're the same speed. latency etc though I'll need to confirm that. I like the idea of having a machine with 32GB - or even 36GB if I keep the existing RAM in - but in the real world would it make any difference?

 

[lucas7004]

Short awnser no. They will interfering with each other and crash your PC.

 

[Calculagator]

[quotemsg=15965849,0,1984864]Short awnser no. They will interfering with each other and crash your PC.[/quotemsg]
????

If the kits are for your model, you shouldn't have a problem with them. Those old server/workstation platforms usually handle RAM pretty well. You may have to install it in a certain order, but different sizes are not usually a problem in this sort of system.
The additional RAM will only help performance if you actually use it. If you don't it won't hurt it, but it will draw quite a bit of power and generate heat.

 

[lucas7004]

Put the kits are different then they would have different volatage, speed and amounts which would definetly entering and crash the PC

 

[Tradesman1]

The mobo supports 32GB in an 8x4GB config so would have strong doubts about that 2x8GB set even working. Also mixing DRAM is basically a 50/50 crapshoot at best, I don't recommend mixing sets, nor do any of the IT pros I network with

 

[Calculagator]

[quotemsg=15965894,0,1984864]Put the kits are different then they would have different volatage, speed and amounts which would definetly entering and crash the PC [/quotemsg]

Are you saying these things from experience or are you just making stuff up? How could they possibly have different voltages if they are both approved for the same machine? I have never had any trouble mixing RAM sizes on Xeon 771 systems as long as the RAM was in pairs. These systems were designed to hold a lot of RAM. They were designed to graciously handle different sizes.

Worst case scenario, the system won't boot. It certainly won't crash. It may not use all of the RAM if it is not installed in the particular order it need/expects.

 

[malcolm-hk]

[quotemsg=15965883,0,1819568]
If the kits are for your model, you shouldn't have a problem with them. Those old server/workstation platforms usually handle RAM pretty well. You may have to install it in a certain order, but different sizes are not usually a problem in this sort of system.
The additional RAM will only help performance if you actually use it. If you don't it won't hurt it, but it will draw quite a bit of power and generate heat.
[/quotemsg]
Thanks for that. I hadn't thought the extra power requirements would be significant.
When you say install the kits in a different order do you mean e.g. install the 16GB, boot and make sure it works, then add the next kit and reboot...?
And I assume i should just use the slots in order - Kit 1 in 1 - 4, kit 2 in 5 -6.

 

[Calculagator]

If I recall correctly, DDR2 FB-DIMMS use 15w or so each.
I'm really not sure what order the t5400 expects. It probably says somewhere on the case. I believe some people have had trouble with certain bios versions getting it to use more the 24GB but may have been able to fix the problem by changing the order of the kits and booting as you suggest.

 

[malcolm-hk]

[quotemsg=15965960,0,1333705]The mobo supports 32GB in an 8x4GB config so would have strong doubts about that 2x8GB set even working. [/quotemsg]

Thanks for that - the guy knew I was looking for more RAM and called me about the 2x8. I hadn't thought to check the maximum stick size.

Well that's one question resolved. And for the other - I'll try the machine with 16GB first and see how it goes.

 

[Calculagator]

I think Tradesman1 is being way too conservative for a testing/old system like yours.
Here's an example of 8GB sticks working just fine on a T5400
http://www.tomshardware.com/forum/57106-2-just-dell-precision-t5400-desktop-server

It is SOP for OEMs to not update their specs even if their machines can really handle much more RAM than advertised: It gives people more reason to upgrade and keeps support simple. Since your system is way outside of warranty or any support contracts, there is no harm in trying. The OEM specs almost never indicate what the machine can actually do, they indicate what Dell is willing to support. I wouldn't recommend it for a new system or a mission critical one, but for an old squeeze-the-budget-for-as-much-as-it-is-worth system I just don't see the harm in trying.

 

[Tradesman1]

While it's definately possible, I prefer to stick with tried and true and based on specs rather than advocate someone go and buy something (especially online) that has nothing proof positive to indicate it even can work. Have seen all to often people saying "yeah, it'll be fine", "sure you can mix sticks, no problem", etc, then someone follows that 'advice' and end up paying return shipping, RMA fees, etc, and that's if it's a place that will even offer refunds. And funny thing, the people offering the advice are never around afterwards, it's not their money thay are throwing away. I prefer to offer honest probabilities of what may, or may not happen. Also if they know up front, they won't be back needing help trying to get mixed DRAM or uncompatible sticks to work, which I spend the bulk of my time here helping people with