875MHz proc on rp7400

[Lacrosse]

I am getting mixed feedback on if you can run 875's on 7400 servers, I would thinks so? but being told I can't from various sources can anyone clarify this for me?
Thanks and by the way Happy New Year

[Patrick Wallek]

Specs for rp7400:
http://www.hp.com/products1/servers/rackoptimized/rp7400/specifications/index.html

Specs for rp7405:
http://www.hp.com/products1/servers/rackoptimized/05series/rp7405/specs.html

Specs for rp7410:
http://www.hp.com/products1/servers/rackoptimized/rp7410/specifications.html

The rp7410 is the only one of those 3 that lists the 875 MHz processors.

[melvyn burnard]

I can find nothing htat says it can be used. The rp9400 and 7410 range can, and it seems thet the rp5400 range can, but not the rp7400.
Anyone else know?

[eric watson]

The highest speed CPU released for the rp7400 is 750 Mhz which is a PA8700 CPU the 875 Mhz CPU's are PA8700+ CPU's. Hope this helps.

[Vincent Farrugia]

Hello,

Another type of system board needs to be made by HP to support PA-8700+ CPUs, making them a total of 4. :-)

HTH,
Vince

[rick jones · Accepted solution]

The rp7400 started life as the N4000. Back then there were 360 and 440 MHz CPUs, and the memory bus was run at 120 MHz.

Since then it has had the memory bus frequency upped to the max of 133 MHz, and has seen three additional CPU frequencies - 550, 650, and 750 MHz. (Ie a total of five CPU frequencies in that box, over a range of 2X, which is about all one can reaonably expect)

While I suppose there are some workloads where the now 5-ish year old memory bus could support 8, 875 MHz CPUs doing useful work, the number of such things is likely rather smaller than it was for 750, 650 and 550 MHz.

Now, the rp7405 and rp7410 have a new and improved memory bus and are much better able to support 8, 875 MHz CPUs doing useful work. Hence, they have support for the 875's and the rp7400 does not.

The rp5470 has the same memory bus as the rp7400, but only supports up to four CPUs, and it is much more plausible for that memory bus to support 4, 875 MHz CPUs. So, 875 MHz CPUs are supported the rp5470.

[Martha Mueller]

It also seems to matter whether you are running HP-UX 11.0 or 11.i. The rp5470 can run the 875 MHz cpu ONLY IF YOU ARE RUNNING HP-UX 11i, not if you are running 11.0. That was a very expensive mistake that was caught for me by my sales rep. He sent the following:

If your running 11.0 you can only go to 750s. The 650s & 750s are PA-8700
chips. When the 875 came out it is been a PA-8700+ chip. This whole +
thing on the end has never been done at HP. Basically, the 8800 isn't
ready and they didn't change anything FUNCTIONALY on the 8700. But they
did change some of the physical construction of the 8700 to make is run
faster. I believe the 11i OS got a patch to deal with this "inbetween"
generation chip. But for 11.0 HP isn't doing anything. So 750s it is.