Need help with Precision T7400 Memory riser

I have the same problem... did this get resolved?

The Precision 690 had four of these connectors, but the T7400 only has two! Are the memory risers different for the T7400?

AFAIK, they're the same. I've seen a picture of a T7400 with four cables.

Two cases particular to me:

1) running lots of virtual machines simultaneously

2) Cache for large databases

Ok, well I actually got another T7400 today, and this one actually had the risers preinstalled.

It turns out that the other two riser power cables are attached to the large P24 connector from the power supply, using a CN-0CR388 cable which splits it into another two memory riser connector cables. Also, the riser version has a different memory fan assembly. Not only is the fan located at the back at the chassis (for obvious reasons), but the plastic assembly is also different, to support the riser boards.

Thanks for the update. You wouldn't happen to know the part numbers for the different pieces so I can try and order them. The support people have no idea what I'm going on about, and I'd rather not resort to buying a new machine!

Please forgive me sticking my nose in here: What use is there for 48GB of RAM. I am new here and just trying to learn.....

Thanks.

Jeff

It just depends what applications you're running on the machine. For "regular" single-user computing you definitely don't need 48GB (yet :P).

I can't speak for the original poster, but I'm a developer working on a distributed system in my spare time, so I need to have multiple machines to test on. To avoid having too many physical machines I host the nodes on multiple virtual machines (VMs) on Hyper-V running on a Precision 690 and two Precision T7400 machines. Each VM requires quite a bit of memory, and that's why the risers come in handy :)

Thank you for the answers! I am coming back to computing after being away for a long, long time. My first 16MB RAM chip cost me around $500. and I thought that I was computing with style!!!!

Jeff

I have a related but different problem, but haven't yet figured out how to start a new thread.

I have a T7400, purchased about two years ago, dual quad-core with memory risers but minimal memory as original equipment.  (My RAM-hungry project had for a second time hit a hard ceiling on supported RAM.  I didn't want to have this problem ever again.)    I have been adding memory in pairs of 2GB SIMMS as I can afford it, installing it all on the first riser board.  (I know this is not in accord with the riser population rules, but the only effect is that memory mode drops from quad to dual.)  When I overflowed onto the second riser board, I noticed that I could not get WIN XP 64 to see more than 16GB.  I had other issues at that time and did not pursue it.  I then got 2 pairs of 4GB SIMMs.  When I finally moved 2 pair of  the 2GB SIMMs to the second riser board and replaced them in the first riser board with the 4GBs, WIN now saw installed memory of 24 GB of RAM.  But I had all this extra 2 GB RAM on the second riser that was being ignored so I began to pursue the problem with Dell chat support.  We decided to remove the risers and work only with the MoBo slots.  We discovered that there was a motherboard problem, wherein memory associated with DIMM slots 3,4,7 & 8 on the Mobo were not counted in the Installed Memory on the setup screen, even though all memory was correctly accounted for in the inventory list.  (The first riser plugs into MoBo slots 1 & 2, the second into slots 3 & 4.)

After the MotherBoard was replaced, all the memory on both riser boards was properly accounted for in the setup display in both the memory inventory and inventory list, but now none of the 4 GB SIMMs that had been working properly until then were tolerated.   I have done extensive experimentation since then and find that one 4GB SIMM works in MoBo slot 1 in single SIMM test mode, and completes the WIN startup.  Sometimes a second 4GB SIMM is slot 2 also works all the way to WIN, sometimes does not even get to the startup ROM, but beeps instead.  Additional SIMMs in any or all the other MoBo slots results in the beeping scenario.  This same applies if two only 4GB SIMMs are installed in DIMMs 1 of risers 1 & 2 (on the first riser board).  The other 14 slots must be empty in order to avoid the beeps and complete the WIN startup.

As long as I do not put the 4GB SIMMs in DIMMs 1 of any riser, I can combine them with any of my 2GB SIMMs in any way permitted by the slot loading rules of the risers, there will be no beeping, and F2 will bring up the startup screen where I can see all the installed memory correctly accounted for in both the inventory list and the installed memory value.  I have seen as much as 36.0 GB in dual channel mode, or 32.0 GB in quad channel mode with the RAM I have.  But now, exiting from the startup screen goes to a dark screen with a frantically blinking underline cursor in the upper left corner.  Eventually the cursor goes away, but WiN never come up.  If I just remove all the 4GB SIMMs WIN comes up just fine.

I truly believe that this behavior will exhibit the same with 4GB SIMMs from Dell (the chat guy suggested my third party RAM at half Dell's price was the source of the problem), but I cannot afford to test this hypothesis. 

Has anyone succeeded in installing more than one pair of 4GB SIMMs in any combination with other RAM, whether from Dell or a third party supplier?

There is an awfully lot of detail here, and I have tried to keep it coherent.  This has been long winded and I apologize for that, but I am hoping somebody will be able to get beyond the riser slot population rules to identify the real problem here.

Jerry

Hi,

I know the thread is very old - but maybe this would be helpful for other people :)

Has anyone succeeded in installing more than one pair of 4GB SIMMs in any combination with other RAM, whether from Dell or a third party supplier?

When you install memory risers - you have in BIOS:

RISER 1 DIMM 1

RISER 2 DIMM 1

RISER 3 DIMM 1

RISER 4 DIMM 1

RISER 1 DIMM 2

RISER 2 DIMM 2

RISER 3 DIMM 2

RISER 4 DIMM 2

...

You need to check what is the RANK of each module - you can't mix 2Rx4 with 2Rx8 in the same "DIMM x" bank/group.

I hope this helps :)

Very Helpful