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Zen 2 questions
- Thread starter mackerel
- Start date
- Joined
- Jun 21, 2002
Not sure if you ever found answers, I'm probably not the best person to answer these questions but I'll try. I assume by uncore you mean SOC voltage. As there are separate dies, my understanding is that the core die runs on vcore and the IO die (memory controller, infinity fabric etc) run on SOC. L3 (in Zen - Zen2, but changed for Zen3) is shared among 4 core units called compute complexes or CCX. My understanding is that latency is induced when a thread is moved from one CCX to another, or other scenarios where cache data is forced the be shuffled around between the compute complexes. From this I may infer (for what it's worth, no guarantee on accuracy) that the L3 is able to communicate with cores within it's own CCX at the CPU clock speed, but must communicate with the IO die or cores outside of the CCX at the fabric speed.
OP
- Joined
- Mar 7, 2008
- Thread Starter
- #3
Thanks for the answer. It was pointed out to me that uncore might be more an Intel term and an AMD one, although my Asrock B450 bios uses the term uncore in places too. SoC is probably more correct to use in that sense.
I've given up on the system now. I believe my CPU is good and the mobo isn't up to sustained loads for it as the CPU was fine in another mobo previously. A positive voltage offset for the cores seems to have eliminated computation errors but I still had a random system level crash. Since I have excess systems anyway I'dd probably sell it off some time.
I've given up on the system now. I believe my CPU is good and the mobo isn't up to sustained loads for it as the CPU was fine in another mobo previously. A positive voltage offset for the cores seems to have eliminated computation errors but I still had a random system level crash. Since I have excess systems anyway I'dd probably sell it off some time.
This is a bit more complicated. There are additional voltages. When you check the BIOS of top OC mobos then you will find two SOC and additional voltages. On cheaper motherboards, some voltages are hidden or are linked to something else. Tbh I wasn't really digging into this topic so I won't tell you exactly what is affecting the L3 cache.
Every motherboard manufacturer is calling everything a bit different what is causing additional confusion when you don't stick with one brand.
I'm playing with 4650G right now and I try to stabilize max APU clocks with high RAM clocks. At first, I thought that the RAM clock affects APU memory as most people are saying that around the web. Well, till some point as in reality in these APU, IF clock = graphics memory clock. So I'm just saying that not everything is so obvious.
One update, maybe not fully related to the main question but somehow may help in something (I hope):
- uncore = uclk = memory controller clock but the voltage can be also called SOC/Uncore or SOC/CPU or something similar, it also affects APU <- can be adjusted with 1:1 or 1:2 ratios, it should be in AMD OC tab if you can't find it elsewhere (on high MSI boards it's in the main tab, in ASUS it's only in AMD tab)
- infinity fabric = fclk = infinity fabric clock but also affects other things <-- this you can adjust as you want but will hit a wall at 1800/1900 on Ryzen 3000/5000 series and 2200/2300 on Ryzen 4000 series
- RAM has a separate clock as you already know
At the lower clock when you set fclk up to 1800MHz then the memory controller will work at 1:1 so also 1800MHz (most motherboards will set that automatically). However, when you set a higher clock then the motherboard will set the memory controller at 1:2... but you can still adjust the fclk above the 1:2 value. One example ... you can set 5000 RAM what gives a 1250MHz memory controller but you can set 1800MHz IF. Depends on the frequency and other factors, it may give you a bit lower latency or higher bandwidth.
Every motherboard manufacturer is calling everything a bit different what is causing additional confusion when you don't stick with one brand.
I'm playing with 4650G right now and I try to stabilize max APU clocks with high RAM clocks. At first, I thought that the RAM clock affects APU memory as most people are saying that around the web. Well, till some point as in reality in these APU, IF clock = graphics memory clock. So I'm just saying that not everything is so obvious.
One update, maybe not fully related to the main question but somehow may help in something (I hope):
- uncore = uclk = memory controller clock but the voltage can be also called SOC/Uncore or SOC/CPU or something similar, it also affects APU <- can be adjusted with 1:1 or 1:2 ratios, it should be in AMD OC tab if you can't find it elsewhere (on high MSI boards it's in the main tab, in ASUS it's only in AMD tab)
- infinity fabric = fclk = infinity fabric clock but also affects other things <-- this you can adjust as you want but will hit a wall at 1800/1900 on Ryzen 3000/5000 series and 2200/2300 on Ryzen 4000 series
- RAM has a separate clock as you already know
At the lower clock when you set fclk up to 1800MHz then the memory controller will work at 1:1 so also 1800MHz (most motherboards will set that automatically). However, when you set a higher clock then the motherboard will set the memory controller at 1:2... but you can still adjust the fclk above the 1:2 value. One example ... you can set 5000 RAM what gives a 1250MHz memory controller but you can set 1800MHz IF. Depends on the frequency and other factors, it may give you a bit lower latency or higher bandwidth.
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