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TUF B550m Gaming-PLUS DIMM Voltage

BuddyW
Level 7
Is there any way to monitor the DIMM voltage on B550m Tuf plus? Would be great to know what the voltage actually is when launched into the OS. It also seems pretty silly to block monitoring it on what is Asus's top-of-line B550 mATX motherboard.
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9 REPLIES 9

thomas_yiu
Level 9
It depends on the RAM. Usually SPD 2133Mhz is 1.2V and 3200Mhz and higher 1.35V to 1.4V.
Sincerely,
TY

thomas_yiu@ROG wrote:
It depends on the RAM. Usually SPD 2133Mhz is 1.2V and 3200Mhz and higher 1.35V to 1.4V.


I'm overclocking my 3200 b-die RAM to 3600 and it needs about 1.45-1.47V to be stable. That's pretty close to the 1.5V limit for DDR4 in 24/7 use. You can see why it's a good idea to know just what voltage it's actually seeing. So let's say I set it to 1.47V in BIOS, if it's acting unstable yet it's actually seeing only 1.45V then I'd not be to worried about upping it another 50mV. But if it's actually seeing 1.49V I'd instead tweak some timings and take the latency hit instead.

It's not exactly putting asus in a good light when this board is supposedly one of the top 'premium' boards in the mATX segment and you have to blind overclock your RAM like this. It's just dumb.

thomas_yiu
Level 9
HWmonitor or any hardware monitor software should show the DRAM voltage.
You can also use AMD Ryzen Master Utility. It shows DRAM Voltag as well.
Sincerely,
TY

thomas_yiu@ROG wrote:
HWmonitor or any hardware monitor software should show the DRAM voltage.
You can also use AMD Ryzen Master Utility. It shows DRAM Voltag as well.


HWMonitor doesn't have anything that looks anywhere close to the DRAM Voltage and neither does HWInfo64 (there are a LOT of sensors with a generic 'VIN nn' label). I haven't tried RyzenMaster, not really sure I want to install it just for this but i may have to just to see if it does.

Silent_Scone
Super Moderator
Hello,

The voltage you see in monitoring depends on where the power line is tapped, and you would need the right equipment (oscilloscope) in order to be able to see any fast transient changes. The actual voltage received will be closer to what is being set.
13900KS / 8000 CAS36 / ROG APEX Z790 / ROG TUF RTX 4090

Silent Scone@ROG wrote:
Hello,

The voltage you see in monitoring depends on where the power line is tapped, and you would need the right equipment (oscilloscope) in order to be able to see any fast transient changes. The actual voltage received will be closer to what is being set.


LOL

The same can be said for any other monitored value...voltage, clock, temps even. So by your logic we should dispense with it all I suppose.

But you're wrong. To many examples of people hooking up a DMM to a voltage test point to find the 'set' value is way off from the 'get' value...mine included. Monitored values may not be perfect, but it beats probing tiny spots on chip-cap solder pads and risking damage.

And besides, I'm talking about DRAM voltage, not CPU voltage. DRAM should be as close to rock steady as possible so if it's fluctuating wildly that alone is important to know so I can get the board RMA'd. And lastly, I'm not looking for ripple or other side-band effects, just average DC values.

Silent_Scone
Super Moderator
BuddyW wrote:
LOL

The same can be said for any other monitored value...voltage, clock, temps even. So by your logic we should dispense with it all I suppose.

But you're wrong. To many examples of people hooking up a DMM to a voltage test point to find the 'set' value is way off from the 'get' value...mine included. Monitored values may not be perfect, but it beats probing tiny spots on chip-cap solder pads and risking damage.

And besides, I'm talking about DRAM voltage, not CPU voltage. DRAM should be as close to rock steady as possible so if it's fluctuating wildly that alone is important to know so I can get the board RMA'd. And lastly, I'm not looking for ripple or other side-band effects, just average DC values.



I'm also talking about DRAM voltage, nobody has mentioned CPU voltage. The real time voltage and the VID are not one and the same. This is why an oscilloscope is needed to confirm whether the DIMM is being subjected to deviation that falls outside of undershoot of two phase power delivery systems.



Comparisons can be a little fruitless depending on the scenario as the measurement points are tapped at different points of the power plane depending on which model you are using. Having points for probing is useful, but for the most accurate reading one would need to take the measurement from the DIMM socket.

Moreover, the voltage is never perfectly constant, so this is also incorrect. Most power delivery circuits are susceptible to transients, and a multi-metre won't be able to pick up on these changes. The applied voltage needs to be adequate enough that it makes allowances for the peak negative undershoot.


Best that we leave these things to electrical engineers and laymen such as us don't go in head strong into these subjects! 🙂
13900KS / 8000 CAS36 / ROG APEX Z790 / ROG TUF RTX 4090

Silent Scone@ROG wrote:
....

Best that we leave these things to electrical engineers and laymen such as us don't go in head strong into these subjects! 🙂


That's such an antidiluvian response that sounds like we should all just ignore monitoring clocks and voltages when tweaking and overclocking (noting you moved the question to a new forum). Let's just go back to the dark ages of blind overclocking, just pump up the voltage and don't worry about it. great.

And no, you don't need an oscilloscope as a responsive DMM works just fine for measuring DC voltages values (that's why they make the darn things) and however imperfect monitoring is it's easily calibrated against one.

thanks for the non-help.

BuddyW wrote:
That's such an antidiluvian response that sounds like we should all just ignore monitoring clocks and voltages when tweaking and overclocking (noting you moved the question to a new forum). Let's just go back to the dark ages of blind overclocking, just pump up the voltage and don't worry about it. great.



I don't have that board to hand so whereas I can't tell you why you're unable to see the VID in HWinfo, the reasoning for what you were asking was another question entirely, and one that cannot be answered correctly without the right methodology as described above.

88707

BuddyW wrote:

And no, you don't need an oscilloscope as a responsive DMM works just fine for measuring DC voltages values (that's why they make the darn things) and however imperfect monitoring is it's easily calibrated against one.

thanks for the non-help.



A volt meter won't be able to show fast load transient changes at peak sag underload so it is not the correct tool for what you're asking. The only advice one can give you beyond what has already been said is to set a VDIMM value you require for stability. Anything short of measuring correctly is futile so would rather not send you up the garden path 🙂

Hope this helps.
13900KS / 8000 CAS36 / ROG APEX Z790 / ROG TUF RTX 4090