vcard RAM question

[morgash]

ok so i started wondering about this the other day and maybe some of u can help me out. the list is as follows.

7900GTX: 1.1ns
7900GT: 1.4ns
7800gtx:1.6ns
7800gt:1.6ns
x1900xt CF Edition: 1.2ns (Samsung K4J52324QC-BJ12)
x1900xt/x: 1.1ns
x1800xt: 1.2ns
x1800xl: 1.4ns

so...the question is this.
x1800xl's are notoriously bad at mem overclocks. GREAT for core but the mem never quite gets where it should. If it is, in fact, 1.4ns RAM like the 7900gt, why then can a x1800xl not easily reach RAM speeds of the x1800xt. the 7900gt reaches 1700mhz with no problems, no volt mod needed. Do a graphite mod and poof u have 2.0ghz on the RAM. For that matter, i havnt seen many if any x1800xt's go that high on the memory either. whats the deal? any enlightenment on this subject would be much appreciated.

Morgash

 

[morgash]

bump

 

[crazylegs]

goos question... not got a clue soz!

BUMP

 

[JPB]

I would like an answer to this question myself....

 

[BassBomb]

heat?

 

[TheRyuu]

Because more that likely they are from different ram manufactures. Take the 7900GTX vs. X1900 for example. Both use 1.1ns ram, right? So it would only make sense that they run at the same speed, right? But howcome the GTX's stock speed is around 1800mhz, while the XTX's stock speed is around 1600mhz? I THINK that it's more than likely because the GTX uses the 1.1ns Samsung Ram, and the XTX uses the Hynix (spelling?) Ram.

It's just a guess, but it also probably has to do with speed binning and yeild rates too. There are more than likely a dozen reasons for not as high overclock. Voltage, heat, etc.

Also just thought of manufacturing process (like 90nm, 65nm, stuff like that, and density of each chip too)

 

[DeathReborn]

Originally posted by: wizboy11
Because more that likely they are from different ram manufactures. Take the 7900GTX vs. X1900 for example. Both use 1.1ns ram, right? So it would only make sense that they run at the same speed, right? But howcome the GTX's stock speed is around 1800mhz, while the XTX's stock speed is around 1600mhz? I THINK that it's more than likely because the GTX uses the 1.1ns Samsung Ram, and the XTX uses the Hynix (spelling?) Ram.

It's just a guess, but it also probably has to do with speed binning and yeild rates too. There are more than likely a dozen reasons for not as high overclock. Voltage, heat, etc.

Also just thought of manufacturing process (like 90nm, 65nm, stuff like that, and density of each chip too)

Let's not forget timings too, ATI may indeed use tighter timings. Also don't the X1900XTX's use Samsung K4J52324QC-BJ11 (1.1ns) too?

Add this to the list, lol

X1900XT CF Edition = 1.2ns (Samsung K4J52324QC-BJ12)

 

[TheRyuu]

Originally posted by: DeathReborn

Originally posted by: wizboy11
Because more that likely they are from different ram manufactures. Take the 7900GTX vs. X1900 for example. Both use 1.1ns ram, right? So it would only make sense that they run at the same speed, right? But howcome the GTX's stock speed is around 1800mhz, while the XTX's stock speed is around 1600mhz? I THINK that it's more than likely because the GTX uses the 1.1ns Samsung Ram, and the XTX uses the Hynix (spelling?) Ram.

It's just a guess, but it also probably has to do with speed binning and yeild rates too. There are more than likely a dozen reasons for not as high overclock. Voltage, heat, etc.

Also just thought of manufacturing process (like 90nm, 65nm, stuff like that, and density of each chip too)

Let's not forget timings too, ATI may indeed use tighter timings. Also don't the X1900XTX's use Samsung K4J52324QC-BJ11 (1.1ns) too?

Add this to the list, lol

X1900XT CF Edition = 1.2ns (Samsung K4J52324QC-BJ12)

Not really sure. I could have sworn that the X1900's used the Hynix chips, but I could be wrong.

 

[morgash]

ur prolly right. however i still wonder whether timings account for the big differences in ability ESPECIALLY between the 7900gt 1.4ns and the x1800xl 1.4ns.

 

[morgash]

ttt

 

[morgash]

ttt

 

[Golgatha]

Originally posted by: wizboy11
Because more that likely they are from different ram manufactures. Take the 7900GTX vs. X1900 for example. Both use 1.1ns ram, right? So it would only make sense that they run at the same speed, right? But howcome the GTX's stock speed is around 1800mhz, while the XTX's stock speed is around 1600mhz? I THINK that it's more than likely because the GTX uses the 1.1ns Samsung Ram, and the XTX uses the Hynix (spelling?) Ram.

It's just a guess, but it also probably has to do with speed binning and yeild rates too. There are more than likely a dozen reasons for not as high overclock. Voltage, heat, etc.

Also just thought of manufacturing process (like 90nm, 65nm, stuff like that, and density of each chip too)

My X1800XT uses Samsung chips. It's all about the timings used for the chips. They can achieve better efficiency using tighter timings.