Just joined to update this thread and say that it is indeed possible to run v4 Broadwell-EX CPUs on an HP DL580 Gen8 (original hardware), even with DDR3 1333Mhz RAM (PC3-10600R).
I was able to confirm two very important details in my testing:
*Swapping a DL580 G8's SPI board with a DL580 G9's SPI board*
- Results in a 'fully converted' G8 into a G9 with no issues and no side-effects (everything works as if it were a G9)
- All iLO functionality works as expected
- G8 chassis no longer accepts v1/v2 CPUs, but does accept v3/v4 CPUs (expected with a G9)
- G8 chassis no longer accepts DDR3 RAM/cartridges, but does accept DDR4 RAM/cartridges (expected with a G9)
*Cross-flashing a DL580 G8's SPI board with the iLO/BIOS firmware from a donor DL580 G9's SPI board*
- Results in a 'mostly converted' G8 into a G9 with some side-effects (detailed further below)
- G8 chassis no longer accepts v1/v2 CPUs, but does accept v3/v4 CPUs (expected with a G9)
- G8 chassis accepts either DDR3 RAM/cartridges *or* DDR4 RAM/cartridges as long as the CPU supports it (unexpected, but welcomed!)
- HTML5-based Remote Console works just fine with the G8 SPI board hardware!
*HP DL580 Gen8 SPI Cross-flash/Broadwell-EX/DDR3 Project*
Project synopsis:
- Sandy Bridge-EX (v1), Ivy Bridge-EX (v2), Haswell-EX (v3) and Broadwell-EX (v4) Xeon CPUs (5 years worth of server CPU generations) all use the same LGA2011-X socket (electrically-compatible)
- Sandy Bridge-EX (v1), Ivy Bridge-EX (v2), Haswell-EX (v3) and Broadwell-EX (v4) Xeon CPUs (5 years worth of server CPU generations) can run on each other's chipsets
- Sandy Bridge-EX (v1) and Ivy Bridge-EX (v2) Xeon CPUs use external voltage regulators (built into motherboard)
- Haswell-EX (v3) and Broadwell-EX (v4) Xeon CPUs use internal voltage regulators (built into CPU)
- Due to the above, v1/v2 Motherboards can accept v3/v4 CPUs without issue *as long as the BIOS allows it* (but most don't... especially Dell and HP BIOSes)
- E7 v4 CPUs (Broadwell-EX, a.k.a. the "top dog" LGA2011-X CPUs) support both DDR3 and DDR4 RAM
- E7 v4 CPUs (Broadwell-EX, a.k.a. the "top dog" LGA2011-X CPUs) include on-die eDRAM cache (doesn't exist on v1/v2 CPUs)
- E7 v4 CPUs (Broadwell-EX, a.k.a. the "top dog" LGA2011-X CPUs) support *both* AVX and AVX2 instructions (v1/v2 CPUs *only* provide AVX)
- E7 v4 CPUs (Broadwell-EX, a.k.a. the "top dog" LGA2011-X CPUs) are a die-shrunk (14nm) version of v3 CPUs (22nm), and thus are more efficient/cooler than v1/v2/v3 CPUs
- HP DL580 Gen8 Servers (my server) supports only v1/v2 CPUs and DDR3 RAM (won't accept v3/v4 CPUs or DDR4 RAM)
- HP DL580 Gen9 Servers (newer version of my server, which I don't own) supports only v3/v4 CPUs and DDR4 RAM (won't accept v1/v2 CPUs or DDR3 RAM)
- I want to run the v4 CPUs, with my DDR3 RAM, on my HP DL580 Gen8 Server... but the G8 BIOS won't allow it (refuses to boot with v4 CPUs, even if I inject the Broadwell microcode into the G8 BIOS it still won't boot)
- Despite the G8 BIOS not working with v4 CPUs or their microcode, I still managed to get this wacky combo (G8 running v4 CPUs and DDR3 RAM) working by dumping the G9 iLO/BIOS firmware from a damaged G9 SPI board and programming it onto my working G8 SPI board with an external programmer (BlackCat USB)
Observed side-effects from programming G9 iLO (2.77)/BIOS (U17) onto G8 SPI board:
- G8 (w/G9 iLO and BIOS flashed) fans run at 50% load 24/7 - fans do not ramp up or down, ever, regardless of Power Settings.
- G8 (w/G9 iLO and BIOS flashed) Serial Number and Product ID show as blank (until I fixed it in the BIOS service menus, easy-peasy)
- G8 (w/G9 iLO and BIOS flashed) boots normally, but I get a yellow-colored (non-blocking) warning/error regarding the REST API (seems the BIOS is sending an API call to the iLO interface/webserver that is returning a 500 Internal Server Error response)
- G8 (w/G9 iLO and BIOS flashed)'s iLO interface reports 'Agentless Management Service' as 'Not available'
- G8 (w/G9 iLO and BIOS flashed)'s iLO interface reports 'Fans' as 'Not available' (which explains the lack of fan control)
- G8 (w/G9 iLO and BIOS flashed)'s iLO interface reports 'Power Supplies' as 'Not available' (however, all Power-related functions in iLO still work as expected - such as the Server Power buttons, Power Regulator, Power Capping, and Power Meter sections)
- G8 (w/G9 iLO and BIOS flashed)'s iLO interface reports 'Temperatures' as 'Not available' (unlike the Power Supplies, the temperature data is indeed missing/non-functional elsewhere in iLO... however the POST screen shows correct Inlet temp, and OS-level utilities also report correct temps such as ESXi)
Aside from the above side-effects, the G8 is totally solid with v4 CPUs and DDR3 RAM running iLO/BIOS firmware from a G9.
I would attach the dumps of the iLO/BIOS firmware from the G9, but i'm guessing it's not allowed - for now I have attached pictures for reference.