I recently swapped motherboards from an ASUS ROG Strix Z790-E, which had a faulty front panel USB-C port, to an ASUS Rog Strix Z790-A. (I realized I didn't need the PCIe 5.0 on the M.2 slot since it removes PCIe lanes from the GPU, so why not save some money?)
Upon switching the motherboards, I noticed that my SP score went up by 1 (from 99 to 100, big whoop!), but that my previous stable undervolt on the Z790-E wasn't stable on the Z790-A.
Previously, I could set CPU Load Line Calibration to 4 with an IA AC Load Line of 0.18 and be fine. Now, using the same CPU LLC, I have to use IA AC Load Line of 0.24 to be stable.
I tested stability using Cinebench R23, y-cruncher and OCCT. I'd pretty much crash the program or BSOD within seconds with y-cruncher when I wasn't stable. After dialing things in, all tests passed, including the main Pi benchmark as well as SFT running for 10+ minutes.
What I also noticed is that although my 3DMark score was pretty much the same-ish for GPU and CPU, my Cinebench score dropped from 40.2k to 38.6k.
Both undervolts were done with enforcing limits and PL1, PL2 set to 253W. So it's strange to see a bit of loss in performance!
I also noticed that on the new motherboard (Z790-A) with 253W, my CPU package temperature never went above 85C. With the old motherboard (Z790-E), my CPU package temperature would go between 87C-91C depending on the ambient temperature of the room.
Playing around with limits, on the new motherboard (Z790-A), I could get my old Cinebench score and be stable in y-cruncher by increasing PL1 and PL2 to 300W as well as upping the IA AC Load Line to .26, this would bring my temps up to 90-91C.
Cinebench isn't that important to me, so I have went ahead and lowered IA AC Load Line to .24 and went back to 253W... but these are just things I've noticed since the switch that I'd like to share.
One more thing, I'm using the same NH-D15 cooler but I'm using NT-H1 thermal paste this time. Last time I was using whatever came with the Thermaltake contact frame (TF7?) because I had ran out of NT-H1 thermal paste previously. (I bought a new tube of NT-H1 when I got the new motherboard.)
I've checked temperatures and nothing is thermal throttling, so I'm guessing all of these things are just due to motherboard variances and maybe the Z790-E driving the CPU a bit harder(?) or more efficient than the Z790-A.
... nothing to lose sleep over, though! Again, just wanted to share!!
TLDR: Swapped motherboards. CB score dropped, IA AC Load Line calibration needs to be increased to keep same undervolt stable.
I'm using the exact same hardware and software on the motherboard. Same CPU, GPU, M.2, RAM, tower, cooling, etc. The M.2 even still has the same Windows install with software as I configured it. Legit the only thing that has changed it the motherboard and thermal paste. But temps on all cores look fine and actually lower than the previous motherboard...
