7870 saphire - getting 430mh/ash on sha-256, but only 280khs on scrypt?

[hoolign]

Any idea why so low? system is a i5 3570 4gb ram and have tried to tweak msi afterburn up a bit but no way its stable after 310~khash

[Spetznaaz]

What is the exact make/model of the card you are using?

[hoolign]

hi, its a saphire, with a pitcairn GPU

[Spetznaaz]

Is it just Sapphire or is it Ghz edition, OC edition, Vapor-x..?

[hoolign]

sorry its a ghz edition

[Spetznaaz]

sorry its a ghz edition

Ok, you most likely have the same problem i had - Where basically the card is fine on sha256, but scrypt it underperforms for no good reason.

The solution is to flash the bios to a non Ghz edition of the card.

I've only done it with the 7970 vapor-x, and i know it 100% works for that card... but there is a chance you could brick your card, unless you have another pc or another card you can use in the unlikely event the new bios didnt work, so you could just flash back to the old one.

It is probably completely fine, but i just wanted to warn you there is the very small chance something could go wrong.

If you want to go ahead and you need help flashing the bios, let me know

Edit - what setting are you currently using, i.e intensity, -g, thread concurrency etc

[hoolign]

oh if you could help me with the flashing that would be great.
 currently best stable i can get id --shaders 1280 --intensity 12 --worksize 256 -g 1

if i put intenstiy at 20 i get about another 15khash but obviously cant use the pc at the same time

[Spetznaaz]

oh if you could help me with the flashing that would be great.
 currently best stable i can get id --shaders 1280 --intensity 12 --worksize 256 -g 1

if i put intenstiy at 20 i get about another 15khash but obviously cant use the pc at the same time

Try intensity 13 -g 1, then I 13 -g2 and I 12 -g 2 quickly.

I'll have to help you out with the flashing tomorrow, it's 4am over here and i gotta go sleep soon lol

[hoolign]

unfortunately didnt have any effect :/ yeah if you could let me know tomorrow that would be awesome, just sha-256ing in the meantime

[Rascal]

1) Read the manual (scrypt-readme)
2) Profit http://img90.imageshack.us/img90/1549/cgminer7870470.jpg

[sololoop]

i got sapphire 7970 vapor-x which only got 520Khs (700+ for normal 7970 card) ; 720++ on sha-256
Then after flash sapphire 7970 (not vapor) rom , i got 750++

[hoolign]

what are your settings rascal?
if i clock my memory over 1350 it just crashes the system?

[mine2mind112]

I haven't a 7870 but for scrypt mining u have to find the right value for memory.....for sha256 u can downclock memory for scrypt u have to overclock it in the right range....for example on my 7970 i use these settings:

core: 985   mem:1410   
core: 1000  mem:1475

u have to do some small change in memory wait 30 second and check the hashrate.

If u are on windows use MSI afterburner for do this.

[hoolign]

yeah im using msi afterburn, and doing small increments but over 1350 mem it starts to crash
1500 mem is a huge increase!

[mine2mind112]

U could try to underclock a little so u have not to go so high with mem

[mine2mind112]

Here somesetting u could try....or maybe just consider some parameters....
https://github.com/litecoin-project/litecoin/wiki/Mining-hardware-comparison#wiki-ATI_AMD_GPUs

[lazydna]

setx GPU_MAX_ALLOC_PERCENT 100
on /cmd

[ewanpa]

good idea

[kgains]

Scrypt is very dependent on memory speed so the core/memery ratio really is the most important criteria. Of course the best way to find the ideal ratio is if someone has already done the work and has found posted it somewhere!

Generally, the core should be roughly 0.7 the speed of the memory. So with a core of 1000MHz that means ~1428MHz. On 7950s I've found these rations to work 1022/1244 or 1100/1500.

For experimenting with rations, I found cgminer the best since unlike when using the GUI front-end (GUIMiner - which anyway uses cgminer), you can change the GPU settings dynamically in the program without having to disconnect. So, just hit <G> <C> etc., change the settings give them a few minutes to get an idea if they work. Repeat until you get your optimal.

BTW, when a SHA-256 coin is close in profitability to scrypt, it makes sense to mine SHA-256 since once you underclock the memory SHA-256 uses a fair bit less energy.

[Rascal]

what are your settings rascal?
if i clock my memory over 1350 it just crashes the system?

1139/1500 - core/mem
tc >22k
i 19
lg 2