Am I right, that he used Pin 9 (Input 3-) to Pin 11 (GND)?
Just for understanding:
- Should it work to another GND-Point too?
- the other Input/Output curcuits (input 1/2/4) can be other voltages (vDD or something) or not used?
- if i modify that Input voltage to 5V instead of 3V3 Rail, can it work higher than 3,1V or i will fire it up? 3,0V is enough for my TCCD, only for research
i did this mod as seen in the picture (before you confirmed that) and works great, thanks!
On 9/28/2021 at 8:13 AM, ludek said:
yes, I remember AsRock had AGP, vDimmRef, vNB, vDimm on one quad-op amp like LM324, impressive
i asked because i only can go up to ~292Mhz BusSpeed, maybe need to try another CPU, because other guys get 320+ without vNB Mod.
On 9/28/2021 at 8:13 AM, ludek said:
in this configuration almost always the power componnent is a power SMD transistor. If your mems eat 1Amp or 2 amps, and vMem is 2.5, from 3V3 rail, the power dissapated on transistor is 3.3-2.5 over 1 Amp is (I=U/R so 3.3-2.5 is 0.8 x 1 is 0.8 W, it's not huge, but if you run full load, the current might jump to few amps) So 1A from 3.3V is 0.8W and from 5V is 5-2.5 x 1 = 2.5 W. This makes huge power losses and hot transistor.
mhh i think i dont get it fully.
the differenz from input and Output voltage multiply by Output current = power dissapated of transistor?
then for example, a RAM about 2,5V and 1A @Stock:
vDimm 2,5V/1A=2,5Ohm @5V Rail = (5V-2,5V)*1A = 2,5W dissipation as you wrote
but if i need 3.5V for same RAM Typ
vDimm 3,5V/2,5Ohm=1,4A @5V Rail = (5V-3,5V)*1,4A = 2,1W dissipation?
with higher Voltage and higher Current less dissipation, i think there is a mistake in calculation.
Comments
thanks for your very quick response!
I know feedback mods, i indentified the LM324 as vDimm Controller but was confused about the Datasheet because there is no FB-Pin, so thanks for your description.
I think i found a post of Lexer https://www.overclock.net/threads/the-socket-939-appreciation-club-and-knowledgebase-official.293448/page-1436#post-26399454
Am I right, that he used Pin 9 (Input 3-) to Pin 11 (GND)?
Just for understanding:
- Should it work to another GND-Point too?
- the other Input/Output curcuits (input 1/2/4) can be other voltages (vDD or something) or not used?
- if i modify that Input voltage to 5V instead of 3V3 Rail, can it work higher than 3,1V or i will fire it up? 3,0V is enough for my TCCD, only for research
i did this mod as seen in the picture (before you confirmed that) and works great, thanks!
i asked because i only can go up to ~292Mhz BusSpeed, maybe need to try another CPU, because other guys get 320+ without vNB Mod.
mhh i think i dont get it fully.
the differenz from input and Output voltage multiply by Output current = power dissapated of transistor?
then for example, a RAM about 2,5V and 1A @Stock:
vDimm 2,5V/1A=2,5Ohm @5V Rail = (5V-2,5V)*1A = 2,5W dissipation as you wrote
but if i need 3.5V for same RAM Typ
vDimm 3,5V/2,5Ohm=1,4A @5V Rail = (5V-3,5V)*1,4A = 2,1W dissipation?
with higher Voltage and higher Current less dissipation, i think there is a mistake in calculation.
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