source: https://www.ngohq.com/unofficial-spectre-patched-bios-for-x58-motherboards.html

Unofficial Spectre Patched BIOS for X58 Motherboards

This folder contains modified BIOSes for X58 motherboards patched with 
the latest microcode (0x1F for Westmere, 0x1D for Bloomfield) against 
all variants of Spectre. Make sure the operating system is also updated 
to be fully protected from speculative execution side-channel vulnerabilities 
(CVE-2017-5715, CVE-2017-5753, CVE-2017-5754).

While most of Nehalem CPUs received a new microcode from Intel, there 
is an early stepping (C0) that hasn't and therefore still vulnerable at 
the moment. However, these very few CPUs will also benefit from increased 
security and stability due to more recent microcode. In addition, the 
ROMs feature TRIM support for SSDs in RAID0 and extended CPU 
compatibility table for all motherboards.

Unofficial ROMs! use at your own risk.