A high capacity PCIe form HSM can sign 7000 SHA-1 Signing per second. So, You application must be talk with HSM and needs to be intragrated into the blockchain system. I dont know if it is better than GPUs but it has some power to do mining operations. Just needs to be talk with Blockchain (API integration).

HSM's are build for securing the private key. But also can be used for signing operations and other PKI platforms/infras. Just look into to this one:  https://safenet.gemalto.com/resources/product-brief/data-protection/Luna_PCI-E_5_0_-_Product_Brief/