T7910 build

Question

Heya, need some advice.History: after 10yrs of running a successful T7600 build for intensive apps and gaming, the time has come where I need AVX2 CPU support. Dig around a little and T7910 looked like the best bet, similar size, feel etc.So I get a mobo, 2xE5-2667v4, 6x16Gb RAM (2Rx4 PC4-2133P, only 6 because that's how many were left at a very good price); start replacing in the T7610 case. Lo and behold, needs PDB...get a PDB. PDB cables don't match...get cables. The PSU (1300W) no match...get PSU. Cables for front I/O no match - at this point I went hands in the air and got a 7910 case with pdb, cables, i/o...the works (it even has the plastic foil on the front, go figure). Assembly time! put everything together, leave 1 CPU just to check if it starts OK, RAM in slots 1-4, move 'le old' CPU cooler and 1080Ti from the other system (I put it back together, works like a charm as usual) and liftoff! to a 2-7 amber light... Now, looking at the RAM placement map I see that for 16gb stick I either put in all slots (8) for CPU0 or mix'n'match 4x16gb with 8x8gb. Am I assuming wrongly that it would start proper with only 1 stick of ram or 2 or 4?NOTE: I enjoy tinkering hardware and this story spans 3months, mostly due to not enough free time but I kind of want to make it work.Suggestions?

kenact71875e · Answer

***CAVEAT***

I don't know how similar the T7910 & T7920 are.

I have not been able to find the Precision_7910_Tower_Technical_Guidebook, but here are the Precision_7920_Tower_Technical_Guidebook CPU/Memory configuration guides.

MEMORY - 2933MHZ AND 3200MHZ
2666MHz and 2933MHz memory RDIMMs have now transitioned to 3200MHz. However 3200MHz memory in the 7920 Tower will not run at that frequency. It will automatically clock down to the maximum frequency supported by the processor which is 2933MHz for Xeon Cascade Lake 82XX Platinum and 62XX Gold processors. With Xeon Cascade Lake Gold 52XX, Silver 42XX and Bronze 32XX processors, memory will clock down to 2666MHz, 2400MHz and 2133MHz speeds respectively. See processor page for details. Note: Precision 7000 system memory SKU descriptions reference 2933MHz or 2666MHz based upon the maximum frequency they can run with Xeon SP Cascade Lake or Sky Lake processors respectively.
Type:
DDR4 SDRAM RDIMM/LRDIMM ECC
Max Frequency
2933MHz
DIMM Slots
24 (12 per CPU)
DIMM Capacities
8GB,16GB, 32GB, 64GB RDIMM, 128GB LRDIMM
Maximum System Memory
3.0TB with 2x “L” CPU SKUs installed)
QUALIFIED MEMORY CONFIGURATIONS:
Note: Not all qualified configurations are necessarily available as standard factory installed options but are possible via CFI or memory customer kits.

user_f54912 · Answer

Thanks for the reply, I have finally arrived at the end of this saga.

I have acquired another complete unit T7910 from eBay at a fair price; I sold 8 x 16Gb RAM for quite a fair sum (thank you AI and ddr crysis).

This one worked "out of the box"!

I have then proceeded to try all the components from the build based on the chassis and motherboard I originally sourced (which wasn't booting) to the working unit.
I have put:

- the 2 CPUs

- 4x 8gb sticks of RAM 2133p (sourced separately; now returned to seller)

- the power supply

- the HDD

- the video card (1080Ti; the one I got came with a K2200)

They all work on the new chassis+mobo.

I have then proceeded to move the components from the new unit to the chassis and mobo I originally sourced. I get the same memory error (amber light combo 2-7); the motherboards are the same model, all parts supported, I was at wits end.

So, right now I'm keeping the working unit I got from eBay (for some odd reason it came with 128Gb instead of 64Gb, the seller said it's fine), with the old 1080Ti, licensed Win (came with Win10, upgraded to Win11 with the reg hack), put 2 other ssd in raid0 for extra storage.
All works fine and dandy.

Now trying to return the initial chassis and mobo I sourced but the seller wants to troubleshoot the mobo. Worst case I take a loss, sell the chassis completely or strip for parts (IO, cables, PDB, PSU) and dumpster the faulty mobo but at least I can work AVX2 software/games and lesson learned...

btw, on the working unit that arrived all RAM slots were working, regardless of the slot placements.

now it's at CPU0:1-2 and CPU1:1-2, 4x32Gb

Precision Fixed Workstations

T7910 build

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