Workstation memory upgrade questions

[Jlankes]

The Problem

My FEA simulations at work are getting too large for my current computer. Specifically Ansys is crashing because it can't allocate enough memory to solve. The second part of the problem is that tech support at Xi sounds more like salesman, and I don't know enough about computers to call them out.

The Setup

Xi Mtower 64-SLi
AMD Athlon 64 X2 3800 dual core AM2 socket
Asus M2N32-SLi Deluxe Motherboard nforce 590
Nvidia Quadro
4 x 1Gb Ram
Windows XP

The Question

The Asus motherboard has 4 Ram slots, so the easy solution would be to switch from 1Gb cards to 2Gb cards for a total of 8Gb, which would easily solve my problems. Both Asus and AMD show on their sites that they can handle 2Gb cards with no problem.

From talking with Xi, I have heard a myriad of reasons from different techies as to why this won't work including:
-The AMD Athlon chips can't handle the 2Gb cards
-The chipset in the Asus motherboard can't handle 2Gb cards
-If the Athlon chips could handle 2Gb cards, they would be selling them
-They tried using 2Gb cards but the system wasn't stable and it didn't really work.

Does anyone have suggestions on this other than just buying the memory and trying it? Or should I just trust Xi, assume that this won't work and persuade my boss to Fork over $4500 for a new box?

 

[Harvey]

Unless you're running a 64 bit version of your OS, your system can't access more than a little over 3 GB of RAM so going to 8 GB wouldn't help.

 

[edcarman]

I would be more inclined to go with the information given by Asus and AMD - Asus' QVL specifically says that four 533MHz 2GB DIMMS will work with the board (bottom of the list). The only thing would be to ensure that you're using the latest BIOS - I have heard stories of the full 8GB not working on certain boards with earlier BIOSs. As for what Xi is saying, my general experience with these type of people is very hit-and-miss. Some of them really know there stuff, others make you wonder how they could be allowed to sell computers.

If you're not willing to take the risk, then you may want to look at a complete system upgrade (although $4500 sounds quite high, especially if you can reuse components such as the Quadro). This would bring about other benefits in addition to the extra RAM.

As an example I get about a 30% reduction in CP time on the same model run on my X2 4800 at home and my Intel E6600 at work. On models where the physical memory requirement is greater than 2GB, I have seen an 50-80% improvement in total run time with 8GB vs 2GB of RAM simply by eliminating the need for swapping to the HD (a situation I'm sure you're familiar with)

Something to note, as Harvey says, is that you would need XP64 to use anything above 4GB. Fortunately, the ANSYS 64-bit software actually works properly with XP64 (unlike some other software) and should be on one of the disks in your software pack.
If you're not already using XP64 then you need to check what software is compatible. Most modern engineering software is and is often available in 64-bit native versions. The problem comes with things like Adobe Acrobat writer (only version 8 works ... sort of) and things like printer drivers (I spent about a week looking for the right drivers after I changed). Also note that if you use old 16-bit DOS and Windows apps, they WILL NOT work within XP64. It is, however, sometimes possible to get around this by running them through DOSBox (someone also suggested that you could run them through an old version of Windows that is running in DOSBox - I haven't yet had to try this though).

 

[Jlankes]

I should have mentioned in my first post that the system is running 64-bit XP (altough that may change to Linux soon).

After reading the Asus QVL it looks like there are 3 memory options for 2Gb cards - Elpida 800 ECC, Kingston 533, and Infineon 533. However, none of these are listed on AMD's recommended memory list. I am assuming that the motherboard compatibility trumps AMD's recommendations, but I just wanted to check on that.

Is there any problems running the ECC memory? Is it even worth the speed increase to go with the DDR2 800 versus the DDR2 533?

 

[edcarman]

I think it would be safe to assume that if the memory is on the Asus QVL, it'll work with the AMD processor. Bear in mind that the QVL is is just the list of memory that the manufacturer has had the opportunity to test. Memory on the QVL is guaranteed to work while other memory, provided it is from a reputable manufacturer, is highly likely to work.
As an example, I use this non-QVL memory Transcend memory on my Gigabyte motherboard with no problems whatsoever.

I don't think there'd be any problems running ECC memory. I've read that it can be a bit slower and it is more expensive than normal RAM.

Someone else will have to answer whether 533MHz is actually slower than 800MHz in normal, non-overclocking applications.