Question AMD Zen4 performance variations at stock... QC /fab problems?

[VirtualLarry]

As usual... it's
Linus... take with an enourmous grain of salt.

 

[Markfw]

I am not going to say I disagree, but its been known by everyone for many years that all chips are not identical. At one time (maybe they are still around ??) you could spend extra to get a tested golden sample chip in the "chip lottery". Nothing has changed in the last 20 years in this regard.

Edit: This is how he makes money, his videos attract people.

 

[moinmoin]

At one time (maybe they are still around ??) you could spend extra to get a tested golden sample chip in the "chip lottery".

Yeah, that was siliconlottery.com, a domain that's now defunct sadly.

 

[gdansk]

Does AMD say they're all the same or that they all meet the specification?

Unfortunately, I have a strict no LTT policy in my household. Der Bauer has a video on a similar subject and most likely did it better.

 

[Det0x]

TLDR, a single 7800x3d out of 12 cpus are underperforming in a single benchmark (1440p CSGO)


When averaged out with more games included


Big fuzz about nothing.. If i were to take a random guess, the single underperforming 7800x3d is a dual CCD unicorn (there were a few out in the wild close to release)

 

[SteinFG]

If i were to take a random guess, the single underforming 7800x3d is a dual CCD unicorn (there were a few out in the wild close to release)

All 7800X3D chips use one CCD. The duall ccd ones have one CCD turned off. Happens when the dual-ccd X3D chip can't be used for 7900X3D or when demand for 7900X3D is low

 

[Det0x]

All 7800X3D chips use one CCD. The duall ccd ones have one CCD turned off. Happens when the dual-ccd X3D chip can't be used for 7900X3D or when demand for 7900X3D is low

And what relevance do you think that have to do with anything i wrote above ?
(nowhere did i hint that i thought it used cores on both CCDs)

Ive binned my part of both vanilla and X3D CCD's over the last year to have a pretty good understanding of the silicon quality on these cpus, but if you think you know something, please do share

Spoiler: atm i have only shared publicly some of my regular 7950x binning results

LLC 5, L3 idle temp ~20 degrees, max load ~60 temp (~185w PPT with 6000/2000 memory)
1200mv vcore set, ~1110mv get under load

Maximum stable 3x in a row Cinebench r23 allcore clocks:
7950x SP 115 (SP 120 + SP 110) = 5400/5300mhz -> 2233 PGE
7950x SP 117 (SP 121 + SP 112) = 5500/5200mhz (6200/2200) (insane CCD0, very bad CCD1)->BQ 2231 PGE
7950x SP 116 (SP 119 + SP 114) = 5450/5350mhz (6200/2100) ->2232 PGY
7950x SP 116 (SP 120 + SP 111) = 5425/5325mhz -> 2233PGE
7950x SP 115 (SP 119 + SP 110) = 5425/5275mhz (6400 maybe 6600 / 2200 -> 2240 SUY
7950x SP 114 (SP 121 + SP 108) = 5450/5250mhz with L0 cache error ->2241 SUY
7950x SP 116 (SP 119 + SP 112) = 5525/5350mhz (6600/2200) ->BQ 2239 SUY
7950x SP 117 (SP 119 + SP 115) = 5350/5275mhz (6600/2200) ->BQ 2333 SUE
7950x SP 119 (SP 120 + SP 118) = 5375/5425mhz (6600/2200) ->BQ 2245 SUY (delidded with direct die cooling)
7950x SP 116 (SP 119 + SP 112) = 5550/5200mhz (6600/2200) ->BQ 2252 SUY

 

[SteinFG]

And what relevance do you think that have to do with anything i wrote above ?

dual CCD 7800X3D perform the same as regular ones, as the second die gets disabled completely. There's 0 difference between there being no die and there being a disabled die

 

[Thibsie]

dual CCD 7800X3D perform the same as regular ones, as the second die gets disabled completely. There's 0 difference between there being no die and there being a disabled die

But slightly higher power (or so I read). Which can influence peak frequency of course.

 

[gdansk]

dual CCD 7800X3D perform the same as regular ones, as the second die gets disabled completely. There's 0 difference between there being no die and there being a disabled die

I think his results match this theory: The dual CCD parts that end up as 7800X3D weren't generally the best silicon quality. That's why they were selected to have a CCD disabled to meet 7800X3D demand.

 

[Thibsie]

Maybe. My 5600X is dual CCD, nothing to do with a X3D part (alas....)