R9 280X bios underclock attempt

I have an XFX R9 280X Black Edition which never gets used any more as I no longer need it for gaming, and it is unstable for compute tasks which is what I chose it for originally. My previous attempts to underclock it through software were unsuccessful, as if it had a minimum that couldn't be overcome.

I just started researching bios modding, and I don't care about the risk of bricking it if I mess up.

I found this: http://www.techpowerup.com/forums/threads/vbe7-vbios-editor-for-radeon-hd-7000-series-cards.189089/

It seems to load the bios file for my card from XFX website and I can put numbers into it, so I intend to try that later, unless anyone has any comment on that. I need to put it back in a machine so I can see what clocks/voltages it current runs at, then decide what to reduce it to. I'll probably aim for stock voltage and clocks, if I can figure out exactly what that is. So, no OC whatsoever. Performance is worthless to me without stability.

Got the card setup and did some baseline testing. Running furmark the system tops out at just over 400W (70W idle) and the GPU thermally throttles at 93C. Factory OC is 1080 core, 1550 ram, 1.2v. I tried underclocking in Crimson and weird stuff happened. No matter what I set, it would bounce between two lower clocks.

BIOS profiles seem to include one at core 1000 1.144v, core 1080 1.2v. I'm thinking, if I copy the lower setting to the higher, that'll bring it into the lower voltage state yet will still be quite overclocked from reference core 900.

The bios on my card was one minor revision older than available too, so I'm going to try the new one unmodified first, before editing clocks.

I got the slightly newer bios both from techpowerup and xfx and a binary comparison showed they're the same. Thinking I didn't want to spend time testing the new bios, as it seemed to be a minor bugfix according to the notes, I went ahead and put in my desired clocks and voltages. Saved, and used the winflash file from xfx. Hmm... not so good... it seems to be stuck, after... longer than you'd expect it should take. Mouse pointer still moves but I can't do anything in Windows. Have I possibly bricked it? I'll give it longer, and have found a recovery guide in case it is somewhat bricked. One tip in that guide, which I hadn't seen before attempting to update, is don't do it in Windows!

Gave up on the Windows flash, reset and... still booted. Good. I made a bootable dos stick and used that. Flashed in an instant and soon I was back in Windows. Here things are not so great. On starting furmark I saw core was at 500 and vram at 150. Not good... really low power, but not what I was expecting. I saw somewhere that a driver re-install might be needed, so doing that now...

Hit it with DDU, reinstalled driver and... success! I'm now running furmark at 1000 core, 1500 ram, 1.143v exactly as I set. I now seem to be hitting thermal throttling at 82C, with a system power draw peaking around 280W.

Why is it throttling at 82C instead of 92C earlier? Is it throttling not on that reported temperature, but something else? I don't see any other reports though.

It is interesting that although I'm reducing the performance settings, it seems to affect idle also. I was getting around 50W system draw before reinstalling driver, and now 60W after. Still less than factory OC.

Now I'm wondering, could I drop the voltage more? This isn't as simple as CPU OC with the need to edit bios files and manually flash... also I need to get a compute stress test for it, other than furmark. On that note, I think I'll try some other (graphical) benchmarks. Didn't take a "before" reading though.

Have you tried Trixx? You can undervolt with it.

My 7970, on which I used to run a 280x bios, is doing 1100/1.1v (Core) 1700/1.55v(vRam).

I hadn't ever heard of that before, but looking it up, sounds good! I'm calling it a night now, but being able to play with clocks and voltages in software is a lot easier than bios, so I hope that will let me dial in good settings and then I can do a further bios update to apply it without software.

I did quickly run some other software... aida64 gpu stress, firestrike, catzilla, steamvr bench... none of those were anywhere like furmark in temps or power usage. Haven't got around to running compute on it yet as that is much more time consuming and manual to set up.

Just tried Trixx... doesn't give voltage control on this card

I'm debating how I could safely go about undervolting now. I don't want to end up with the situation where I set inappropriate values so it wont boot, so I'm thinking I'll try, say, 1.100v and drop the clock further, then only overclock the clock to find the stable limit.

1.1v seems to be working fine at 1000 core. I had weirdness when I dropped it further though. Tried 1.05v, and the clocks seemed to be stuck low. If I play about with Trixx sometimes I can get it high again, but this seemed too unreliable to use.

ok, stop just using furmark, that's like trying to tow the titanic with a chevy s10.
just use heaven benchmark, we have all given up on furmark.

That isn't a significant factor right now. Is there a reason for the card to clock weirdly if I try to bios set <1.1v? I do think it would go lower if it would behave. Note this doesn't seem to be a stability thing. If it clocks ok at lower voltage it seems fine, but sometimes it gets in a state where it doesn't go out of low performance mode.