First, HP has no 10Gbase-T SFP+ transceiver. If you want to connect using copper, you schould invest in a native 10GBase-T linecard (HP 8-port 10GBase-T v2 zl Module J9546A or HP 8p 1/2.5/5/XGT PoE+ v3 zl2 Module J9995A) or, as you indicated SFP+ Direct Attach Cables, but then you need to have SFP+ interfaces.
However, a DAC, just like an optical transceiver, carries a brand ID. HP doesn't support DACs with a non HP ID (verify the switch datasheet for compatible cables). For my experience, your interfaces dont come up on a 5400 platform with non (or unsupported) HP accessories. The same can apply to a server NIC, although they tend to be more fexible in the cable branding. You should also keep in mind that DAC only exitst in limited distance. In general 10GBase-T is more flexible to work with.
A DAC is nothing like a 10Gbase-T cable, 10Gbase T uses UTP cabling (Cat 6 and better) where you should look at a DAC as being transceivers with an electric in stead of optical cable in between them.