Tasselhoof
#0
Hej, jeg sad og læste lidt om voltmod til 9800xt, og faldt over dette lille problem..
Der står i denne beskrivelse at den normale modstand (volten til vpuén) ligger på 1620ohm ( 1.6kohm) men det som undre mig, er at de skriver man skal bruge en 22000ohm ( 22kohm ) modstand til moddet!!
ER der nogen der ved om der ikke skulle stå 2kohm omdstand.. For de 22000 ohm lyder da forkert, hvis man skal sænke modstanden til under de 1620okm??
Our measurements showed 1.78V VPU voltage, but the combination at the input of the chip corresponded to 1.4V. It meant that there was another way for changing the VPU voltage, besides changing the bit combination on the input. I didn't like the idea of cutting and soldering lines on the PCB and had to read the specifications of the FAN5240 to find another way. According to the specs, pins 17 and 18 of the chip (marked as VCore Output Sense) serve for voltage control as well as for protection and monitoring. The typical connection circuit from the manufacturer differed from what we saw on our graphics card: there was an R1597 resistor with a resistance of 1620Ohm between pins 17 and 18. In fact, pin 17 was connected to the common output. So, I decided to connect a trimming 22kOhm resistor in parallel to the R1597.
Der står i denne beskrivelse at den normale modstand (volten til vpuén) ligger på 1620ohm ( 1.6kohm) men det som undre mig, er at de skriver man skal bruge en 22000ohm ( 22kohm ) modstand til moddet!!
ER der nogen der ved om der ikke skulle stå 2kohm omdstand.. For de 22000 ohm lyder da forkert, hvis man skal sænke modstanden til under de 1620okm??
Our measurements showed 1.78V VPU voltage, but the combination at the input of the chip corresponded to 1.4V. It meant that there was another way for changing the VPU voltage, besides changing the bit combination on the input. I didn't like the idea of cutting and soldering lines on the PCB and had to read the specifications of the FAN5240 to find another way. According to the specs, pins 17 and 18 of the chip (marked as VCore Output Sense) serve for voltage control as well as for protection and monitoring. The typical connection circuit from the manufacturer differed from what we saw on our graphics card: there was an R1597 resistor with a resistance of 1620Ohm between pins 17 and 18. In fact, pin 17 was connected to the common output. So, I decided to connect a trimming 22kOhm resistor in parallel to the R1597.
#1
Hvor har du fundet dette mod på nettet ?
Det de lader til at have gjort er at sætte et potmetet på sammen med den 1520 ohm´s medstand for at sænke denne, så du skal vist ikke montere en 22Kogm sammen med, men have fundet deres "værdi" dvs hvad satte de potmeteret på ? Hvilken modstand ?
På mit FX kort skulle jeg skifte en modstand ud, fra den 0 ohm der sad til en 22Kohm, dvs i.flg X-Bit lab sluttede de ved 33Kohm, men jeg har ikke så travlt og den 22 jeg har monteret giver et udemærket resultat :e
Det de lader til at have gjort er at sætte et potmetet på sammen med den 1520 ohm´s medstand for at sænke denne, så du skal vist ikke montere en 22Kogm sammen med, men have fundet deres "værdi" dvs hvad satte de potmeteret på ? Hvilken modstand ?
På mit FX kort skulle jeg skifte en modstand ud, fra den 0 ohm der sad til en 22Kohm, dvs i.flg X-Bit lab sluttede de ved 33Kohm, men jeg har ikke så travlt og den 22 jeg har monteret giver et udemærket resultat :e
#2
#3
Sådan som jeg har forstået det, skal man sænke modstanden så den kommer under de 1620ohm for at hæve vcoren..
#4
#5
Her står der at de stoppede ved en modstand på 4.8kohm, så det skal nok passe med de 22kohm, synes bare det lyd helt vild.. :r
I soldered one wire from the trimming resistor to pin 18 of the
FAN5240 chip, and the other wire to a small bond area next to and attached to the R1597 resistor.
We took our measurements from the point marked as VCore in the scheme.
Our idea was correct, as the Vcore was growing when we were reducing the resistance of the trimming resistor. We stopped on 1.9V, when the trimming resistor stayed at 4.8kOhm. As a result, we made the VPU work at 500MHz. The card was actually stable at 510-520MHz core frequency, but produced some visual artifacts in 3D, so we made it work at 500MHz in our performance tests.
I soldered one wire from the trimming resistor to pin 18 of the
FAN5240 chip, and the other wire to a small bond area next to and attached to the R1597 resistor.
We took our measurements from the point marked as VCore in the scheme.
Our idea was correct, as the Vcore was growing when we were reducing the resistance of the trimming resistor. We stopped on 1.9V, when the trimming resistor stayed at 4.8kOhm. As a result, we made the VPU work at 500MHz. The card was actually stable at 510-520MHz core frequency, but produced some visual artifacts in 3D, so we made it work at 500MHz in our performance tests.
#6
We stopped on 1.9V, when the trimming resistor stayed at 4.8kOhm
Der står at de brugte et trim potmeter på 22Kohm, men læse 4,8Kohm var værdien de stoppede ved fordi der ramte de 1.9v på coren. Så du skal lodde en 4,8KOhm sammen med den 1620 ohm der sidder derpå, eller fjerne den 1620´er for at skifte den ud med en på ..... ja hvordan er ohm´s lov lige med to paralle modstande.......
Hmm hvor ligger bogen nu henne ?
Be right back...
Der står at de brugte et trim potmeter på 22Kohm, men læse 4,8Kohm var værdien de stoppede ved fordi der ramte de 1.9v på coren. Så du skal lodde en 4,8KOhm sammen med den 1620 ohm der sidder derpå, eller fjerne den 1620´er for at skifte den ud med en på ..... ja hvordan er ohm´s lov lige med to paralle modstande.......
Hmm hvor ligger bogen nu henne ?
Be right back...
#7
Her var den :D
Den siger at:
Ved parallele modstande bliver værdien:
1/1620+ 1/4800=1/x det kan omskrives til :
1620*4800/1620+4800=7776000/6420=1211,2ohm
Det er altså den værdi som R1597 resistor skal have, dvs fjern den og monter denne istedet, ja altså en i nærmeste størrelse.
Den siger at:
Ved parallele modstande bliver værdien:
1/1620+ 1/4800=1/x det kan omskrives til :
1620*4800/1620+4800=7776000/6420=1211,2ohm
Det er altså den værdi som R1597 resistor skal have, dvs fjern den og monter denne istedet, ja altså en i nærmeste størrelse.