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PCI slots underpowered on rx16x0 ?

 
Richard Schmidt
Occasional Contributor

PCI slots underpowered on rx16x0 ?

We are attempting to migrate an application from
HP A180C and A500 servers to the rx1620. We use two Symmetricom bc635U-PCI cards, each rated 350 ma. We find we can only support one of these on the rx1600 and rx1620 (2-PCI-X slots). With two we get boot fail with "PCI slot exceeds power limit". (One card plus one B5509 LAN PCI card works,though.) This failure is unexpected, as we can boot up four of these Symmetricom cards on an rx2620 (4-slot) server. Our rx1600's have only one CPU. Their power supply is rated 3.5 amps @ 3.3 volts. HP says the power is limited in firmware (IO_PCI_POWER_OVERLOAD_ERR). Anyone know if that is true? Is it set too low? The old A180C has only a 300W power supply vs. the rx1620's 400W power supply, but its 3.3v power was a whopping 20 amps!

Did we buy the wrong (2-slot) Itanium server?
6 REPLIES 6
Sameer_Nirmal
Honored Contributor

Re: PCI slots underpowered on rx16x0 ?

Hi Richard,

As per the specification of rx1600 and rx1620, the PCI IO Expansion supports one PCI card of 25W OR two 15W cards.

rx2620 PCI IO expansion supports 4 independent PCI 15W cards.

You might want to check the power consumption of the Symmetricom card. If two cards power consumption exceed the limit maybe >30W, then what you see is obvious on rx1600/20 servers.

I think there is a power consumption threshold being set ( as supported by the hardware design ) in the BMC firmware. If power consumption exceed the threshold of PCI IO , you would see the error given by firmware. The threshold setting is required to avoid possible damage to the system.
jaap prenger
Occasional Advisor

Re: PCI slots underpowered on rx16x0 ?

According to the datasheet of the bc635PCI-U on http://www.symmttm.com/pdf/Bus/DS_bc635PCI-U.pdf this pci card has the following power requirements: +5V @ 350mA, +12V @ 400mA and -12V @ 70mA. Total power consumption is 7.4W for a single card so two cards should be no problem (<15W).

The firmware might give the (misleading) errormessage as a precautionary message because it does not recognize the bc635U card and assumes it is a high performance (read: high power consumption) card.

Can anyone confirm or disprove this behaviour?
Alan_152
Honored Contributor

Re: PCI slots underpowered on rx16x0 ?

There are a couple of known issues with power supply to the 16xx PCI slots. There are combinations on the approved component list that have since been proved invalid.

I don't see the Symmetricons on the approved tested list, so I don't know about them. Keep in mind that although they run at 350ma, they might power up at a higher burst amperage. The 26xx has a different backplane design from the 16xx, so that kind of comparison is invalid (and, BTW, the 4640 is even more finicky, because of the private/public backplane design -- some cards combinations there that are otherwise approved won't work in certain slot combinations).

However, you might try updating the system firmware in case some of the power limits have been relaxed.
Richard Schmidt
Occasional Contributor

Re: PCI slots underpowered on rx16x0 ?

Thanks for your comments folks. One of the rx1620's is fresh from HP and there have been no firmware releases in about a year. I hoped that this forum would inspire the rx16x0 design team to look at the firmware power limit which seems to be set at less than 50% of the 15W power limit on the second slot, and Jaap confirms our calculations. My sales rep communicated with the design team but found little interest in the problem.

The important clue from our test on the rx2620 is that each of four cards was happy with its "15W" power, but the "15W" slot on the rx16x0 is quite clearly inadequately powered and does not meet published specs.
That internal power supply is rated to provide enough current for ten 3.3v Symmetricom cards!

A firmware fix might possibly raise the overload limit, else the rx2620 is our own costly fix.

Alan_152
Honored Contributor

Re: PCI slots underpowered on rx16x0 ?

I wouldn't count on a freshly shipped unit coming with latest firmware. Current production is 3.15. No mention of any changes in the voltage limits in this revisions release notes, but that could have come earlier...
Richard Schmidt
Occasional Contributor

Re: PCI slots underpowered on rx16x0 ?

Actully HP is quite good about f/w on build-to-order systems.
For rx16x0:
3.15 is (optional) MP ILO f/w.
2.18 [4511] (ROM date 3/2005) is the current system f/w
3.48 is BMC f/w

See patch PHSS_33092,Post Date: 05/06/28