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I just got a second hand 280X. connected it into my ETH rig and.. voila, 15Mh.

The card is running at pretty high clocks. about 1070/1550. is this normal? I was expecting around 20Mh but the DAG file is pretty large by now.

It sounds about right. I have a few r9 280's as well and they are also now hashing at about 15MH/s. The days of 20 are long gone with these cards.

Didn't know it's going to be this low. should have purchased a 290X instead  :-\

try 1070/1500 - you will get more ))

You need to hack the bios and you'll get 18.5mh/s

how to hack the bios. Will you please explain it ?

change memory straps and raise memory clock.

this all will not help a lot. Old tahiti have tlb problems accessing large memory arrays

all my 7950/7970/280x run at 18mhs or so with no issues. Except being power hungry. 10W/1MHS

What custom bios are you using?

Read this

http://www.overclock.net/t/1554360/tahiti-memory-timings-patch-for-hynix-vram

I get about 17 on stock bios at 1100/1500

Sometimes due to how the memory timings table is set up, slower runs FASTER.

please tell me if it is safe to do or not. And what driver I should try. I run on win 7 64 bit with 7950 AMD gpu

Hacking the memory timings is safe, worse case you will get hardware errors and need to revert back.

However its near impossible to get 18MH/s with these 280x currently. Best to just dual mine with them.

Perfectly possible :)

This is an option but what is also already told in other topics that this is not smart because the lifetime will be shorter and you will void your warranty too.

Yes changing bios does void warranty which is already over for most 280x.

Look Ma,... no BIOS change...   ;D



https://i.imgur.com/TTSbHvG.png?1

Really curious as to why you would censor your pool name. It looks like its most likely ethpool.

I'm curious as well and it's definitely ethpool. but can you share clockspeeds please?

Sure.

https://i.imgur.com/2yb2Wht.png

Core 1170 will get you at that speed yeah..

Not sure how you get such low temps but my 280X already runs at 80c without that high of a clock speed.

I've been able to squeeze a bit above 15mh but that's a lot of fans required to keep it cool

Those temperatures are possible at this overclock only with water cooling!

or it is cold in his place

I get about 12 MH/s. I undervolt it to 0.86V and run at core/memory 800/1000MHz. My electriicty price is high.

Yea, he probably lives in a cold country. I doubt someone has a custom loop with so many cards.

How much is 7970/ 280x doing on EXP currently? Could be more profitable for tahiti owners?

Its like 30-40% faster but the pay is less so in the end you make the same amount. The calculators aren't accurate.

It also uses a little more power.

Wrong. No water cooling. Sapphire Vapor-X. Down volt with Trixx. Soon or a later I will have to dismantle and change cooling adhesive at the one that can't keep with other's low temperatures. And I didn't blow dust from them for almost a year.  ::)

I used to have 2 x 280Xs in my rigs and I sold them on Ebay because they use SO MUCH electricity for a pretty low hash-rate. I had them core overclocked to 1150 and they did 17-18mh/s. Far better to use a 380. With a 380 at core 800, mem 1500 I get 20-21mh/s and using much less power. Or a 290/x at core 1100 mem 1125 gets me 30mh/s but uses a lot of power.

There was some discussion earlier about how flashing a BIOS would void warranty? Who would still have a 280X under warranty anyway? They are about 4 years old aren't they?

If you underbvolt the 390, to about 1.000V and 970MHz, you can get about 27.5 MH/s. But use a lot less power.

What voltage are yours set to run at 1170Mhz core?

Problem running at that large Mhz is that you need a high voltage and they become very bad at power consumption.

I run most of mine at around 1V and it runs 1070/1600

Depend on card: 1.137 or 1.112V. At 1070 they can run on 1.087 stable. Changing them (slowly) for 480 and 470.

So they use about 175Watts each correct?

Huh, never disconnected one to do precise measurement. Two rigs 5x280x and 1x290, 1x470, 2x480 pulling 1,65kW from wall for 200+MH/s

If I had to guess

5x 280x = 180Watts each X 5 = 900
290 = 250 Watts
470,480 = 150 Watts x 3 = 450 Watts

Total ~ 1600

What is the best driver version to mine etc or eth in AMD 7950?  I am asking the question in different thread but no one replied.

The one that gives you undervolting capability with Afterburner or Trix. 15.7.1 works for me.

How to undervolt and is it safe for my gpu? What should i expect from a single and 7950 gpu in eth mining now?

Undervolting is totally safe and it even brings down the heat and power usage. I am getting 15Mh from a 280X, I think you can expect anywhere near that since it's the same chip.

Please share any link to teach me how to undervolt a gpu?

If you're using Claymore GPU miner, then you can even use it's own under-volt command. Check out the Read-Me file of the miner in this case. Simply edit the command in the start file of the miner and you'll be good to go.

What're the values of voltage which GPU-Z is currently providing to you by the way? You can first try the similar value in the under-clocking, then lower it down and test continuously till you feel that something is going wrong with the hash-rate or GPU driver.

You can use MSI afterburner to undervolt.

I have R9 280x. How much can I undervolt ?

You can run at 950 mV and 850 MHz. It depends on the quality of the card. That is more or less ballpark figure.

850 MHz with GPU Clock or Memory Clock ? I have 1070/1600MHz default values.

850MHz will be with core clock. The memory clock has to be 1250 MHz to have proper speed with Claymore miner.