AMD Platform vs GIGABYTE: IO Power Overhead Gone

Starting off with the big change for toady’s review: the new production-grade GIGABYTE Milan compatible test platform.

In our original review of Milan, we had initially discovered that AMD’s newest generation chips had one large glass jaw: the platform’s extremely high idle package power behaviour exceeding 100W. This was a notable regression compared to what we saw on Rome, and we deemed it as a core cause as of why Milan was seeing some performance regressions in certain workloads compared to the predecessor Rome SKUs.

We had communicated our findings and worries to AMD prior to the review publishing, but never root-caused the issue, and never were able to confirm whether this was the intended behaviour of the new Milan chips or not. We theorized that it was a side-effect of the new sIOD which had the infinity fabric running at a higher frequency, which this generation runs in 1:1 mode with the memory controller clocks.

Package Idle Power

To our surprise, when setting up the new GIGABYTE system, we found out that this behaviour of extremely high idle power was not being exhibited on the new test platform.

Indeed, instead of the 100W idle figures as we had tested on the Daytona system, we’re now seeing figures that are pretty much in line with AMD’s Rome system, at around 65-72W. The biggest discrepancy was found in the 75F3 part, which now idles 39W less than on the Daytona system.

Milan Power Efficiency
TDP Setting 280W
Perf PKG
500.perlbench_r 281 274 166 317 282 195
502.gcc_r 262 262 131 271 265 150
505.mcf_r 155 252 115 158 252 132
520.omnetpp_r 142 249 120 144 244 133
523.xalancbmk_r 181 261 131 195 266 152
525.x264_r 602 279 172 641 283 196
531.deepsjeng_r 262 267 161 296 283 196
541.leela_r 267 249 148 303 274 199
548.exchange2_r 487 274 176 543 262 202
557.xz_r 190 260 141 206 272 171
SPECint2017 255 260 141 275 265 164
kJ Total   2029     1932  
Score / W   0.980     1.037  
503.bwaves_r 354 226 90 362 218 99
507.cactuBSSN_r 222 278 150 229 285 174
508.namd_r 282 279 176 280 260 193
510.parest_r 153 256 119 162 259 138
511.povray_r 348 275 176 387 255 193
519.lbm_r 39 219 84 40 210 92
526.blender_r 372 276 165 396 282 188
527.cam4_r 399 278 147 417 285 170
538.imagick_r 446 278 178 471 268 200
544.nab_r 259 278 175 275 282 198
549.fotonik3d_r 110 220 86 113 215 95
554.roms_r 88 243 106 89 241 119
SPECfp2017 211 240 110 220 235 123
kJ Total   4980     4716  
Score / W   0.879     0.9361  

A more detailed power analysis of the EPYC 7763 during our SPEC2017 runs confirms the change in the power behaviour. Although the total average package power hasn’t changed much between the systems, in the integer suite now 5W higher at 265W vs 260W, and in the FP suite now 5W lower at 235W vs 240W, what more significantly changes is the core power allocation which is now much higher on the GIGABYTE system.

In core-bound workloads with little memory pressure, such as 541.leela_r, the core power of the EPYC 7763 went up from 148W to 199W, a +51W increase or +34%. Naturally because of this core power increase, there’s also a corresponding large performance increase of +13.3%.

The behaviour change doesn’t apply to every workload, memory-heavy workloads such as 519.lbm don’t see much of a change in power behaviour, and only showcase a small performance boost.

Reviewing the performance differences between the original Daytona system tested figures and the new GIGABYTE motherboard test-runs, we’re seeing some significant performance boosts across the board, with many 10-13% increases in compute bound and core-power bound workloads.

These figures are significant enough that they do change the overall verdict of those SKUs, and they also change the tone of our final review verdict on Milan, as evidently the one weakness the new generation had was actually not a design mishap, but actually was an issue with the Daytona system. It explains a lot of the more lacklustre performance increases of Milan vs Rome, and we’re happy that this was ultimately not an issue for production-grade platforms.

As a note, because we also have the 4-chiplet EPYC 7443 and EPYC 7343 SKUs in-house now, we also measured the platform idle power of those units, which came in at 50 and 52W. This is actually quite a bit below the 65-75W of the 8-chiplet 7763, 75F3 and 72F3 parts, which indicates that this power behaviour isn’t solely internal to the sIOD chiplet, but actually part of the sIOD and CCD interfaces, or as well the CCD L3 cache power.


Test Bed and Setup - Compiler Options SPEC - Multi-Threaded Performance - Subscores
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  • DannyH246 - Thursday, July 1, 2021 - link

    lol - no need to be subtle about it. has been doing this for years.
  • Qasar - Thursday, July 1, 2021 - link

    hilarious, go back to wccftech then danny
  • whatthe123 - Friday, June 25, 2021 - link

    good god man, the review quite literally posts hard numbers of epyc simply thrashing xeon in performance even on a per core basis, and you think they're worried that intel will retaliate against them if they don't say something nice about one corner of a segment of performance?

    what is it about technology that attracts cultists?
  • Threska - Saturday, June 26, 2021 - link

    There's a reason the PCMasterRace forum exists.
  • msroadkill612 - Sunday, June 27, 2021 - link

    "Cultists" - I like it :)

    So true, & on many levels. I see strangely neurotic behaviour from such an allegedly smart & rational demographic.

    As a group, they are prone to be great at rattling off streams of presumably accurate numbers and jargon, but arrive at childishly naive conclusions, & ask the wrong questions based plain wrong premises.
  • devione - Sunday, June 27, 2021 - link

    Jesus Christ man. Grow some fucking balls. If you're going to call out Anandtech for being biased at least be straightforward and frank. No need to write an essay trying to couch and justify and be obtuse about it
  • Makste - Monday, July 5, 2021 - link

  • Oxford Guy - Friday, June 25, 2021 - link

    What are the RAM timings? I don’t see that information in the charts.
  • Andrei Frumusanu - Saturday, June 26, 2021 - link

    These are standardised PC4-3200AA-RB2-12 sticks, running at JEDEC timings.
  • Oxford Guy - Monday, June 28, 2021 - link

    Thank you. And the other systems tested?

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