Topic: Powercolor AX6870X2 @ Newegg for $450 - page 2. (Read 6775 times)

i'm not sure.  it has been mentioned that if you flash the bios and you run under linux, the settings work. 
under windows the drivers can not load and cause a reboot loop or the always friendly bsod.

it would be great if we could have this confirmed or dispelled.

if it's true under linux, i'd switch for temp and power savings.  otherwise i wouldn't bother.

It's probably a hardware timing limitation.

Nope...

contacted Powercolor, this was their reply:
"This is restricted by AMD, we can not make memory speed run too low.
        Maybe you can try MSI Afterburner to see if it can do this."

followed up regarding MSI AB, pointing out that that's not an issue.  restated the lowering memory limitation by 100 only... waiting for another response.

also contacted AMD, haven't heard back from them yet.

Really was hoping someone here would be interested in working together on this, but maybe there aren't too many 6870s in use by miners.

Any luck? Also as a side question to anyone does a 6870 reference card perform better then 300 megahash?

so....

i learned how to flash BIOS.  whoo-hoo!! relatively simple in the end...

however, it's not working on 6870 and I suspect on 6990s as well, based on feedback on these forums. (unless ppl are keeping it secret )

There is hope though!

One thing is clear: when you flash a bios to these cards, the cards run and output display and all seem just fine without catalyst drivers under windows.

As soon as the drivers begin to load however, the system reboots.  this is under windows 7 64bit in my case.

this doesn't make any sense.  the pricks obviously have put something in the driver that is able to "read" from the card if the bios is flashed with different settings then stock bios.  bastards!!!

so, i don't feel like spending more time on this today, but this needs to be tried on linux.  flash from usb stick, then boot into linux and see how it behaves.  It seems that some of you might have tried this already? any feedback on this?

Another possibility, but this is beyond my technical capabilities at the moment, is to load up some kind of a low-level monitor that can tell us what exactly is a video card "sending" to driver when it has been flashed.  I bet, well it's a hunch really, that there's some flag/register or something that gets set and the driver crashes.  so, maybe it would be possible to write a "fixer" driver/program that would intercept this bullshit and allow the driver in windows to load.

if anyone is interested in pursuing this in tandem, let me know, but this fucking memory bullshit with 6990s and 6870s is pissing me off. no reason for this to be happening.

299Mhashes @ 940/840

at 950/850 driver begins to crash.  i'm running 11.8

temps are 75s but that's because it's in a system with 2 6990s with about 1 inch between the cards.

this card should be able to run pretty cool without 6990s in the system (or open case obviously).  powercolor did a decent job on the heatpipes which are exposed, not covered by plastic cover at top and bottom of the card.

so hows the overclock of AX6870x2?? hash rate

thanks

this particular clock does not behave like 6990 wrt memory. 

you can only lower the mem by 100. NOT 125.

i actually went a step further than what i posted in that thread. the one i linked shows that it couldn't be done by software with all 4 of my different 6xxx cards, so i used RBE bios editor to manually decrease the memory clocks (leaving all other settings the same), then flashed it with the new modded bios and i get BSOD on all flashed cards. then i just flashed back to stock bios and quit. i read on another computer forum, something about the new 6xxx series that the engineers locked these cards, so flashing with "out of spec" bios will cause bsod. that probably explains why trying lower memory speeds way down will cause it not to stick to the settings

only a few lucky 6xxx cards are memory flashable, so even if someone started a thread on a successful 6xxx memory flash, then it works for that specific card, but not the card you currently have. but if i do see some post about it, i'll post it here

Sigh.... yeah, I'm fully aware of the limitations and I saw your thread before.  I'm not asking about limitations or arguing whether the setting take or not.

I'm actually trying to get to these lower settings by flashing the bios.  if you can point me to relevant threads of people who have done it, that would be more helpful.  I don't need posts to threads on steps to flashing.  already got those.

6xxx series cards has problems when decreasing memory clocks or trying to flash them. only a few people supposedly unclocked them to the 200-300mhz range successfully, but for the most part you can't underclock the memory that low. that's why i stick to the 5xxx series for the easiness of tweakability. refer to this thread i started about memory underclocking for the 6xxx series cards:

https://bitcointalksearch.org/topic/heads-up-hd6xxx-memory-does-not-actually-underclock-31013

Pretty sure your in new territory. I don't think many people have messed with the 68xx series cards.

I've heard tell that you might have to remove the ATI drivers before rebooting into Windows, can't confirm since I'm a linux guy.  I had setup a Win7 system for flashing my 6950s and had the exact same issue, but didn't have time to dig into it then. 

From what I've read all of the 6xxx series cards have this memory clock limitation.  The value is 125mHz, however, so at 900mHz GPU you should be able to use 775mHz memory clock.  At least that's the case on my 6950's, which I run at 885/760.

I've also heard tell that flashed 6xxx series cards that won't boot into Windows work in linux just fine, I've yet to try this either however.  I need to pull one of my cards soon so I'll give that a try in a few days.

first off, this 6870 behaves like the 6990s.  you can only lower memory by 100 less than the speed setting...

So... no dice on flashing 6870 BIOS....

I flashed it and when windows is booting up, right after the splash screen, the system just reboots and goes into "windows error recovery" mode
I can choose automatically try to fix error blah blah blah
or start windows normally.
neither option improves anything.

if i disconnect power on the 6870 and let the system boot, it loads up just fine.

gonna flash the bios to original i guess....

Anyone flash a 6870 BIOS successfully, or a 6990?  please chime in.

only some 6xxx series cards can underclock memory, some can't. have you tried underclocking the memory when the card is in the system by itself? i'm wondering if the inability to underclock memory is due to the card itself or if it's because the 6990 is also in there.

How low are you currently able to clock the memory?

mike, I hope to provide more info.  I'm currently searching for the guide on how to flash the bios.  for some reason, I'm having problems with underclocking memory on the 6870 in a system where I have 2 6990s + 1 of these 6870x2.  I'm hoping to flash the memory to 350 and see how far I can push the OC then.

While I can't speak with 100% certainty, I believe that overall, the 6870 is a slightly less powerful GPU than the 5830 and despite its lower power consumption which may or may not yield higher stable frequencies, the hardware comparison page seems to indicate that the 6870 has gotten a solid amount of attention from overclockers with entries of 1050 and even 1075mhz, but no hash rates exceeding the 5830's documented limits. You asked if it was a more stable card, and it very well may be. It seems, however, that the 6870 is unable to exceed the 5830's speeds.

bump.

I really want this answered if possible.

I got a question about the 6870 vs 5830. They are basically the exact same card except the 6870 requires less power. Since a 6870 needs less power to run at the same speeds as a 5830 would that mean a 6870 is more stable at the 1000+ mhz  core clock mark then a 5830? The reason I ask is because I'm curious if the 6870 got the same attention the 5830 did would it exceed the 5830's record speeds?