General > General Technical Chat
New PC build p0rn photos.
Howardlong:
--- Quote from: paulca on April 14, 2022, 09:38:50 am ---Server != Workstation != Gaming Desktop.
--- End quote ---
Very true.
Here's the email machine I built over the past year, RTX 3090 and 5950x.
Useless for server stuff as it only has 32GB RAM. I've found that it does play Flight Simulator in VR reasonably well though.
For my day to day productivity, I run an 11th gen i7 NUC w/64GB RAM & 2TB Gen 4 NVMe SSD.
My laptop of choice is an LG Gram 17 2020 w/40GB RAM 10th Gen i7 with 4TB NVMe SSD, which, as well as having the best laptop screen I've ever encountered, for embedded dev it enjoys great I/O including 3 x USB A 3.1, so no dongle world for me.
For servers, I have two headless dual socket 24c/48t Ivy Bridge era boxes, one with 64GB and the other with 192GB, for spinning up multiple VMs to test out infrastructure projects.
Of interest is that if you spin up a VM in the cloud, there's still a fair bit of Ivy Bridge hanging around, although more modern power efficient stuff is coming along to replace it.
paulca:
So I finally found the key to the cage they were keeping the CPU horsepower in.
It's a 3.8Ghz base clock and max boost of 4.8Ghz. Yes sure I've seen it hit 4.7+Ghz, but when I give it a full 16 threads of prime calculations and FFTs it heats up and drops, eventually to 3.8-3.9Ghz. Most people would just shrug and accept that.
Nope. There is the concept of the voltage curves. Basically as the clock goes up the core needs more voltage to be stable. So as clocks go up, die power goes up. There is a hard limiter on 120W total die power. However my motherboard has awesome VRMs with uber stable voltage at up to 200Amps... so I found the curve offset settings and dropped the whole curve by 30mV. The furthest it will go without getting nasty with it.
Now when it was pushed hard it didn't reach that power limiter until it was happily boost clocking on all cores to 4.7Ghz. So having maxed out the benchmark for multi-threading, leaving every other 8 core way, way behind and tripping on the heels of the 16 core threadripper ahead... I moved onto single threading.
Here the magic is in the AMD percision boost overdrive system and... primary max boost clock. Straight away it was slamming it's two "golden cores" to max boost clock of 4850Mhz and alternating them to prevent the individual cores thermal throttling. It shuts off all the other cores, leaving the 2 primary single thread cores and 1 core to run everything else. Doing everything it can to keep that one thread at absolutely max performance.
Of course my cooling system with the -30mV under volt didn't seem all that stressed and the CPU was churning through stress tests and benchmarks, beating even the Intel chips and leading the leader board (on Cinebench). But I still wanted to crash the thing. So I went digging for what else I could turn up.
Found the Max boost clock override. Did a quick bit of maths and said, "Will it do a full 5Ghz?" and set it to +200Mhz and ran the benchmark. It actually worked with single cores boosting to 5050Mhz.
Then the screens went black and it rebooted. I was able to complete benchmarks and get scores, but I had another 2 instant resets and another thing morning. So, it's not stable. I think I might just take that 200Mhz down to 150Mhz and see.
And, yes, placebo effect or not, I did notice the desktop feel more snappy and boot time come down the first time it booted with the 30mV under volt. Over all it's about 25% faster over all. Oddly it's not producing much more heat, the CPU socket power went from ~130W to ~150W which isn't exactly a big leap in thermals.
paulca:
Because it boots and runs single threaded and multi-threaded benchmarks and seems to only crash on the desktop, I suspect the 5050Mhz max boost which is applied to all cores is too much for one (or more) of the lesser cores. The main "golden cores" handle it fine, but occasionally if one of the lesser cores gets boosted to 5050Mhz it might make an error, if that operation cannot be repipelined or if it create an unrecoverable CPU fault, then it's night night.
So, maybe I should look at per-core max boost clocks and take the lesser 6 cores down 20Mhz at a time until no more resets.
Maybe I could go even higher on the golden-cores.
Berni:
Yep power is the most important thing in overclocking.
If you can give it more power and cool that power then you can give it more voltage to get higher clocks. But this eventually gets into diminishing returns where it takes more and more power for smaller and smaller gains.
For this reason i don't tend to overclock any of my CPUs. The only thing i do is crank up the power limit to something like 150W in the bios to just let the CPU pull as much juice as it wants to, usually this makes the CPU run at max boost clock on all cores when under heavy load, but has no effect when under light load. It doesn't tend to cause any instability (unless the motherboard can't keep up with delivering this much power) Thing is not all benchmarks make the CPU produce the same amount of heat even tho they all hold it pegged at 100% utilization. Some instructions or combinations of instructions take more power to execute, this is especially apparent for the new AVX512 instructions that do a massive amount of math in parallel.
As for overclocks crashing during light load but stable during a benchmark, this is typically the fault of the CPU pulling too sharp of a power spike (when switching clock speed), making the core voltage regulation too slow to respond. This is why huge overclocks tend to lock the CPU freqency to be max all the time, but this is obviously a very bad idea for every day use since the CPU will be burning tons of power even when just sitting on a desktop. Not like you are going to notice the slight performance gain.
PlainName:
--- Quote ---Useless for server stuff as it only has 32GB RAM
--- End quote ---
!
!!
My mail and DNS (and some other stuff) server has 3GB memory. Surely it depends on what the server's function is - 'server' covers as many variations as 'vehicle', and a 5-litre turbo-charged V12 isn't necessary for mowing the lawn (although it could be fun).
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