What if AMD FX had "real" cores? [video]
10 comments
·September 18, 2025HankStallone
doublepg23
Definitely worth replacing for the performance at this point but is it possible it just needs a repaste? Thermal paste would’ve definitely dried out over 10 years and cause overheating symptoms.
Yizahi
They were real though. How many ALU were there on say FX-8350? 8 ALUs. How many FPUs were there? 8 FPU each 128 bit wide. What alternative definition of core whis doesn't satisfy? CPU was underperforming at that time and Intel fans were trying to equate their Hyperthreading with AMDs core organization, but they were always real cores.
dragontamer
8 Integer ALUs, 4 Vector FPUs, 8x L1 d-caches but only 4x L2 d-Caches.
And perhaps most importantly: 4x decoders/4x L1 iCache. IIRC, the entire damn chip was decoder-bound.
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Note: AMD Zen has 4x Integer pipelines and 4x FPU pipelines __PER CORE__. Modern high-performance systems CANNOT have a single 2x-pipeline FPU shared between two cores (averaging one pipeline per core). Modern Zen is closer to 4x pipelines per core, maybe more depending on how you count load/store units.
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dannyw
Yup. The limited decoders meant your pipeline just wasn’t flowing every cycle, because many of the stages were sitting idle.
dragontamer
Note that Intel's modern e-Core has 3x decoders per core. When code is straight, they alternate (decoder#1 / decoder#2 / decoder#3). When code is branchy, they split up across different jumps aka if/else statements.
Shrinking the decoder on Bulldozer was clearly the wrong move for Fx-series / AMD. Today's chips are going wide decoder (ex: Apple can do 8x decode per clock tick), deep opcode cache (AMD Zen has a large opcode cache allowing for 6x way lookup per clocktick), or Intel's new and interesting multiple-decoder thing.
magicalhippo
I'm a bit curious why this couldn't have been covered earlier by simply having the OS disable some cores on a 4-module 8-thread part. After all the video does point out that if only one thread uses one module, it as full access to all the resources of the module.
Also, the benchmark is clock-for-clock, so while the older Phenom II looks like it's ahead, the Buldozer should be able to go faster still.
All that said, I really enjoyed this retrospective look.
stn8188
That was a neat video, I wasn't aware of the FX architecture in that detail. I loved my FX series... I had a 6300 that got me through engineering school, and now the same basic desktop serves as my kids' gaming computer (though I was able to upgrade to a cheap 8350). It definitely still holds it's own with the older games that I let the kids play!
dannyw
It was good value! There’s few good value CPU’s sadly. I remember using my ryzen 3300x for years and years; it got me by on a budget.
I'm actually replacing the FX-8350 in my fileserver next week, because I was running ffmpeg on it and it kept crashing about a minute into the job, so I assume it was overheating either the CPU or something on the motherboard.
It's almost 10 years old, so I can't complain. And I think I got a check for $2 or something like that from the class-action suit.