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Dell R750xa JPJ1ZP3, 2x RTX 6000 Ada to be fitted, ComfyUI's new home at NH3. Diffing Dell's factory CSV against the reseller invoice shows four downgrades: half the RAM, the 2400 W PSUs, and the GPU risers, cables and high-performance fans all absent. Records the resolved GPU power chain, correcting my own first answer: the chassis' CPU 8-pin cabling is the right source type and NVIDIA 930-00030-1546-000 bridges it to the card's 12VHPWR, so the PCIe-type RCCWC I first proposed is withdrawn. Also closes the NVMe question — the backplane is SAS/SATA only — and notes that free PCIe slots may moot it. Auto-archival fired at 308 lines; seven entries moved to archival-memory.md. The 250-line target was not reached because the guards hold nearly everything else back as under 14 days or carrying open deferred work.
5.2 KiB
[2026-09-01] The Ada inference server is a Dell R750xa bought used — and the reseller stripped four things Dell shipped
Dell PowerEdge R750xa, service tag JPJ1ZP3, 8-bay 2.5" 2U. Bought from Entera Source
(invoice INV-74422, 2026-08-25). 2× NVIDIA RTX 6000 Ada 48 GB to be fitted — confirmed by
the operator, NOT L40/L40S. Destination NH3. This is ComfyUI's new home; the GX10 is a
separate machine → 2026-09-01-pfi-gx10-onboarding.
As bought
CPU 2x Xeon Silver 4314 16C/32T each = 32C/64T, 135 W each
RAM 8x Micron 16 GB PC4-3200 = 128 GB
NIC dual 25 GbE SFP28 (Broadcom 57414, OCP 3.0)
boot BOSS-S2 + 2x 240 GB M.2 SATA, mirrored
storage 2x 1.92 TB SATA SSD (Hynix), 6 of 8 bays free
HBA PERC HBA355i (LSI SAS3816)
PSU 2x 1400 W Platinum
THE DIFF — factory CSV (JPJ1ZP3.csv, booth 54-puffin) vs the invoice
| Dell factory | reseller invoice | |
|---|---|---|
| RAM | 16× 16 GB M04W6, "Performance Optimized" = 256 GB |
8× = 128 GB |
| PSU | 2400 W redundant (450-AJEV) |
2× 1400 W (7DWXY) |
| GPUs | 4× Tesla V100-32GB passive (490-BHUC) |
none |
| GPU risers | 12XPY (right DW), 9TR6X (left DW) |
not listed |
| GPU cables | 470-AEVS 4-GPU kit: 4RW1P W4K7M XC48N 6C77X |
not listed |
| Riser cables | signal CP67W CXYF8 H4D7D N61TK; power HXJDR W1P56; pad C2JNP |
not listed |
| Fans | 6× FD00R Very High Performance |
not listed |
| Controller | PERC H345 | HBA355i — an UPGRADE for us |
| Drives | 2× 480 GB | 2× 1.92 TB |
⚠ "Not listed on the invoice" is not proof of removal. Operator will pull an iDRAC inventory to settle it. Diff that against the CSV rather than the invoice.
The GPU power chain — resolved, and my first answer was wrong
RTX 6000 Ada: 300 W, ACTIVE cooling, one 16-pin 12VHPWR (CEM5) connector (nvidia.com).
The R750xa kit 470-AEVS is "W/CPU CONN" — CPU/EPS 8-pin, because V100 takes that. I
initially flagged this as a mismatch requiring the PCIe-type cable RCCWC / Dell
470-BBXH. That was wrong and is withdrawn — RCCWC is for H100/L40/L40S.
NVIDIA sells the bridge for exactly this case:
930-00030-1546-000— NVIDIA Power Cable, RTX 6000 Ada Generation, 1× CPU 8-Pin → 1× CEM5 16-Pin
So the chain is 470-AEVS CPU 8-pin → 930-00030-1546-000 → card. The chassis' existing
cabling is the correct source type. Two adapters needed, one per card.
⚠ Factory brackets are VFYGM — the V100S extended bracket. RTX 6000 Ada is a different
physical card; bracket fit is UNKNOWN, check at fitting.
⚠ Active cooling in a passive-card chassis. Six high-performance fans expect to push air through passive cards; the RTX 6000 Ada has its own blower. It works in practice, but Dell never validated this combination for this box.
Storage — NVMe in the drive bays is CLOSED
Factory backplane is 321-BGKG : 2.5" Chassis with up to 8 **SAS/SATA** Drives. Not
NVMe-capable; bays would need a backplane swap.
Arithmetic if filling bays with SATA:
2x SATA (today) ~1.1 GB/s
6x striped ~3.3 GB/s <- roughly ONE NVMe drive
8x striped ~4.4 GB/s
backplane ceiling ~6 GB/s (8 lanes x SATA III)
The HBA355i (PCIe 4.0 x8) is nowhere near limiting. Drives are the constraint.
ARC probably beats spindles here. ComfyUI reloads the same checkpoints; with the factory 256 GB restored, ZFS ARC caches most of the working set at RAM speed. The RAM upgrade is both cheaper and likely faster than four more SATA drives.
UNCHECKED, and it may moot the whole bay question: free PCIe slots. Riser Config 0 is
330-BBUM : Riser Config 0, 6x16 + 2x8 slots; two double-wide GPUs will not consume all of
it. An NVMe add-in card (U.2 HBA or bifurcating M.2 carrier) bypasses the SAS/SATA backplane
entirely. Add slot inventory to the iDRAC pull.
Power — the ceiling is deliberate now, not discovered later
2x RTX 6000 Ada 600 W
2x Xeon 4314 270 W
rest ~150 W
~1,020 W sustained
One 1400 W PSU carries that, so redundancy holds. But factory specced 2400 W for four V100s: there is no headroom for a third or fourth GPU. And ~1 kW is the same class as ana-ml2, the box whose training run tripped a breaker on 2026-08-26 — decide which NH3 circuit this lands on before racking, not after.
Buy list
Certain:
| item | part | qty |
|---|---|---|
| RDIMM 16 GB 3200 2Rx8 | M04W6 |
8 → restores 256 GB, all 16 slots, all 8 channels/socket |
| NVIDIA 12VHPWR adapter | 930-00030-1546-000 |
2 |
Only if the iDRAC inventory shows them absent: 12XPY, 9TR6X, 4RW1P, W4K7M,
XC48N, 6C77X, CP67W, CXYF8, H4D7D, N61TK, HXJDR, W1P56, C2JNP,
FD00R ×6.
Spend order: RAM → check PCIe slots → only then consider more SATA drives.
⚠ Dell's Installation & Service Manual publishes no part numbers at all for GPU kit hardware — names and quantities only. The factory CSV keyed to the service tag is the only authoritative source of DPNs for this machine. Do not accept a five-character DPN from anywhere else without corroboration.