[SOLVED] CPU/MOBO Compatibility: More than Socket + Chipset?

[donnyluvd2bowl]

Just had something I've never experienced happen. Putting a system together, I spec'd out a particular mobo and cpu, correct socket and compatible chipset. Couldn't get the machine to POST so I called the mobo company (Supermicro) and after conferring with their engineering dept, they told me the board and CPU weren't compatible.

So, is there something ELSE that one needs to consider? I've been doing home-builds for 15 years about, and I've never encountered this. Did I miss something? Here are the two components ftr:

X11DDW-NT with a Xeon W-3175x

But both 3647 socket and work with a C620 series/Lewisberg chipset.

 

[jojesa]

According to Supermicro specification it does support 2nd Gen Intel Xeon Scalable Processors (Cascade Lake-SP), Dual Socket P (LGA 3647) with up to 205 W TDP like the Xeon W-3275
The Xeon W-3175X has a 255W TDP, which exceed the power delivery of that motherboard.

 

[donnyluvd2bowl]

isn't TDP just an issue of cooling though?

 

[jojesa]

isn't TDP just an issue of cooling though?

Sort of...
Even though Intel website says that TDP is a heat dissipation measurement, the numbers show more and many manufacturers use it in correlation to power draw.
A higher TDP CPU will draw more power.
255W is the TDP of the CPU at base frequency (3.1GHz), so the TDP could be higher than 350W when it reaches Turbo frequency of 3.8GHz.

There is a correlation with TDP and power consumption.
The Xeon X2155 has a 140W TDP and it draws around 139W at base frequency.
The Core i9-9900k has a 95W TDP and it draws around 99W at base frequency.
AMD Ryzen 7 2700X has a 105W TDP and it draws 108W at base frequency.
Of course all those CPU draw a lot more power when running at higher Boost frequencies .

 

[donnyluvd2bowl]

oh interesting. so i guess with that said, I'm looking to replace the 3175's and I'm thinking either the Gold 6246 or 6254.

The 6254 has more cores and the base speed is essentially comparable but the 6246 has a lower TDP (200w for 6254 vs 165w for 6246) at base frequency which means I'm more likely to have the headroom to get it to it's max frequency (4.2GHZ), yeah?

 

[jojesa]

That sounds about right.
You could get a list of compatible and tested CPUs from Supermicro support.

 

[Mr.Spock]

TDP may be only a spec - but the mfr may have left support out of the bios (not intending to support it) so the microcode may not be there

similarly certain AM4 motherboards no longer support older AM4 APUs as there was only so much room on bios once they added Gen 2 Ryzen support