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Go to SolutionT640 experiments with H750/H755
Hi all,
I have two dell T640 systems.
One of them has the 16x2.5 backplane and works great with an H750 and the 04Y34G cable. (single SFF-8654 to dual SFF-8643 - BP_A and BP_B)
However, for my other T640 with the 18x3.5 LFF backplane, I tried using an H755.
Since the H755 has two SFF-8654 connectors, I tried using two 04Y34G cables and tried to make sure to using only BP_A cable for the first cable and the BP_B cable for the second 04Y34G cable.
Everything worked great -BUT- the iDRAC kept saying that both BP cables were not properly connected.
The first T640 works great and without any kind of warnings but it has an H750 HBA.
Is there a set of cables I could buy that could play nice with both ports on a full H755 going to the BP_A and BP_B SFF-8643 ports on a 14th gen backplane?
@DELL-Bridjet V, thank you for taking the time to make such an elaborate answer. I actually have an H750 in my other T640 (the one with a 16x2.5 backplane. From your reply, I gather I could use the H750 with the T640 that has the 18x3.5 backplane and keep the H755 in the T640 with the 16x2.5 backplane.
What cables would I need to do that? Do you mind sharing the cable part numbers for an H755 with the 16x2.5 backplane?
Thank you,
Vincent
DELL-Bridjet V
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Posted September 15th, 2026 08:16
Hi @ElCoyote_,
Regarding the H755 controller card compatible with the 16 x 2.5" backplane on the T640 server, the only part number I was able to locate is 4Y34G, which I believe is the same one you already have.
Regards,DELL-Bridjet V
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DELL-Bridjet V
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DELL-Bridjet V
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Posted September 1st, 2026 11:48
Hi @ElCoyote_,
The H755 controller is not compatible with the 18×3.5" LFF backplane in the Dell T640, as this backplane has only a single SAS connector (A0_B0), whereas the H755 expects dual backplane connections. This mismatch is what causes the persistent iDRAC cable warnings.
Recommended options:
In short, the solution is to match the controller to the backplane: H750 for 18×3.5" or H755 with 16×2.5 or ignore the iDRAC cable warning to continue with the current connection.
Regards,
DELL-Bridjet V
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Regards,
DELL-Bridjet V
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