This is a kernel/firmware/CMOS issue in my experience. And not easy to resolve as it happens very low down in the s/w stack - which means h/w vendor can point finger at o/s vendor, with o/s vendor pointing fingers at both h/w vendor and Oracle (as the cluster/RAC vendor running on top of the o/s).
As for a support case with vendor.. the first time this happened (back in 2009) with us, the support cases (one with h/w vendor and one with o/s vendor) came to naught. Neither accept responsibility for the error with both parties saying the error is not triggered by their product. Never did log an Oracle SR as I told both parties that blaming the problem on s/w higher up the s/w stack is not only idiotic, but not acceptable. (if I had my way, I would have thrown out the h/w - management was far more forgiving)
We eventually sorted the problem (kind of) with a specific CMOS/firmware version. The issue is still there - but it happens very infrequently. With later firmware versions the soft CPU lockup rears its head as soon as any real loads are processed on the platform.
Interestingly, I have the same problem again on very similar hardware that you have, with Oracle Linux 6.5. You need to file a support case with both HP and Redhat - and optionally Oracle (but do not expect Oracle to fix h/w and kernel issues for h/w and kernel they do not support or own).