Re: Cost of handling misaligned access

On 2/8/2025 6:30 AM, Anssi Saari wrote:

BGB <cr88192@gmail.com> writes:
 

If one runs their CPU at 4 GHz, then under multi-threaded load, it may
hit 70C or so, frequency starts jumping all over (as it tries to keep
temperature under control), and sometimes the computer will crash.

 To me that sounds more like inadequate cooling. When I last upgraded my
desktop together I ran Prime95 torture test for a few hours. Temperature
stabilized below where the CPU cores would throttle to cool down, which
was expected. No crashes or wrong results either. This is just a basic
game capable AMD Ryzen 5 5600X 6-Core system, I don't have logs of the
clock speeds or temps from back then.

I have typically used the stock coolers.
With the AMD-FX (FX-8350, TDP=125W; Piledriver), the stock cooler was IIRC roughly a 2.5" x 2.5" x 2" generic aluminum heatsink with a fan (nothing fancy, a block of aluminum with fins, and a fan; generally the fan ran fast and loud, *1).
It was too hot and unstable at the stock 4GHz, but running it at 3.6 (and with turbo boost disabled) made it run cooler and more stable.
Before doing so, under load it would sometimes try to boost up temporarily, and then drop to much lower speeds (IIRC, around 500MHz or something), then up and down, often followed by a BSOD. Post-drop, it could run stable at near 100% CPU load.
*1: Though, on the scale of things, it was still quieter than a 2008 era Xeon rack server I have (was discarded), which when running, sounds kinda like a vacuum cleaner. People complaining about cooling fan noise could maybe try running one of these... For its crapton of RAM sticks, still only has 8GB of RAM though. CPU is dual quad cores running at 2.3 GHz.
No GPU, no real ability to add a GPU (lacks a PCIe X16 slot). Onboard graphics chipset lacks any form of 3D acceleration.
I mostly use it occasionally for HDD copying tasks (was running CentOS, sadly CentOS has since been discontinued...).
My current CPU (Ryzen-7 7200X, TDP=105W; Zen+), came with a larger heatsink (flares out at the top, has heat-pipes and a bigger fan). AKA: "AMD Wraith Cooler". The fan runs slower, so less noise.
CPU speed is still mostly stock on this one, can note:
   Stock base speed is 3.7 GHz;
   At 1 or 2 cores active, it may jump to around 4 GHz;
   At 50% CPU load, it runs at around 3.90 GHz.
   At 100% CPU load, it drops to around 3.45 GHz.
Runs stable enough at stock that I haven't needed to bother with it.
For a lot of the stuff I am doing, I don't care as much about maximum single thread performance, but ability to run stable at full CPU load is relevant.
IIRC, running RAM at 2667 MT/s, unganged mode (have usually had better results in unganged mode in my tests).
RAM configuration is wonky 3x 32GB + 1x 16GB.
   2x 32GB + 2x 16GB = 96 GB
   3x 32GB + 1x 16GB = 112 GB
   4x 32GB = 128GB (But crap goes wonky, only 4GB usable).
Didn't notice any performance or stability differences between the 96GB and 112GB configurations, but the 112GB configuration has the merit of 16GB more RAM (and I had bought 4 sticks mistakenly thinking I could use all of them, otherwise I would have just bought 2 sticks and gone with 96, ...).
Despite claiming 3200 MT/s on the box, the RAM sticks themselves claim to be 2133 MT/s, and are not stable at 3200 or 2933 MT/s, but do run OK at 2667 MT/s. No RGB LEDs, does still have an aggressive aluminum heat-sink design though.
Personally, I have little reason to care about RGB, but people now stick RGB LEDs on pretty much everything PC related it seems.
...