OC problems w/ X1900XT isolated?

[tjpark1111]

I've been reading more and more posts about how their X1900XT won't overclock so well, so I was wondering what other owners think about this, and if it is really isolated. It is known that the 1900 downclocks itself(along with voltage drop)when in 2D mode to save power, and I was thinking it's obviously in 2D mode(underclocked) when someone is just running ATI tool and a few other things in the background to overclock. So, I was wondering if the people who had problems might try to overclock after a short session of gaming(so the clock speed goes back up), meaning alt+tab right out of a game then try to overclock. I think because of the voltage drop that goes with the underclock, some haven't been getting good results. Of course, I'm still not as good as experts like you guys around here, so I'm just speculating.

 

[TraumaRN]

You maybe slightly onto something, I discovered my more stable clocks on my 7800GT when it was in my old apartment when it idled higher. Higher being 43C with the stock cooler. Now that I am in a better and more cool place with my computer it idles around 35C with stock cooler and my overclock jumped up a little bit and while I've had no problems at the new higher clocks I know that as soon as I move in the fall I'll probably lower then again.

The clocks in my sig were from my old apartment, now I'm running stable and at 35Cidle and about 56C load @ 536/1230

Of course I have an nVidia card but mine does downclock as well.

 

[LittleNemoNES]

I think that the cards just get too damn hot to promise any more OCing. I flashed my XT bios to XTX but I can't really take it any higher than that. 10 points more on the core = crash. 15 on the mem=artifacts. Oh well, at least I saved $100

 

[Munky]

When overclocking the x1900 cards people disable the automatic 2d downclocking, and manually raise the voltage. Otherwise the card wont even run at stock 3d speeds using 2d voltage. But I also think that the main reason people dont see high overclocks is because of the heat output of the card. While you can easily raise the voltage to increase an overclock, you'd ideally need watercooling to keep the temps within reasonable limits.

 

[jim1976]

I think it has to do with a couple of things..
1.Memory controller (much weaker in XTs) thus much lower clocks in memory. I'm guessing that it affects core too, since I managed to increase my core from 670(stock HSF) to 720(vgpu 1.475 and vddci 1.5) but anything higher than that gives poor yields for the much higher voltage in proportion and heat isn't an issue..
2.2nd pick BJ11 thus lower than 800MHz clocks.. The vast majority of XTXs reach 850+ , while most XTs barely reach 800-820..

I cannot take my RAM beyond 815 regardless of the VDDCI bump I give,it immediately throws artifacts in ATItool..

 

[Dman877]

Seems like ati is just hitting clockspeed limitations on their current process (they're on .09 or .11? I forgot). Anyway, it seems like a process reduction (like what nv just did with the 7800/7900) would do wonders for the ati cards.

 

[jim1976]

Originally posted by: Dman877
Seems like ati is just hitting clockspeed limitations on their current process (they're on .09 or .11? I forgot). Anyway, it seems like a process reduction (like what nv just did with the 7800/7900) would do wonders for the ati cards.

Well many guys at XS are hitting great O/Cs with their XTs as well.. But obviously you have a much higher o/cing potential with the XTXs they seem to be cherry picked cores.. Besides that as far as concerns your other comment going to 80nm won't do a thing with the O/C potential unless it will be low-k...

 

[Fistandantilis]

I can hit XTX speeds with my 1900xt with no problems at all, I havent tried to go higher though. I tried the auto detect function but it kept on locking up, so I just set it to XTX speeds tested it and set it as a profile... been on that profile ever since, that was a few weeks ago.