Bitcoin Forum

Was on verge of getting 7950s but reading about lower power use etc on 7790 makes me think might be better
off in long run? I think 7950 will do roughly 2x a 7790.

For mining alt coins not BTC

for script based coins I would go with the 7950 because of the faster vram bandwith.

for sha256  2 * 7790 less heat and power

my 2¢ ;D

thanks for info!

All the reports I've seen of the 7790 for Scrypt are very, very bad.. Something in the area of 180 - 230 khash. Given the price, its not a good decision. However, there are multiple users that are reporting ~300 mhash for sha256-based mining. That is pretty darn good. May be worth it if you really want sha256-based mining.

which makes the least heat compared to hashes?

My 7790 results...

296 mhash (guiminer -v -w 128 -f 1 1200/200)
246 khash (cgminer, tc 8000, w 128, i 17, 830/1500)

I have three and they hardly use any power. I'm running them stacked in a case and the fans are so quiet I can't hear them.

That said, I am looking to build a rig with 2x7950 or some other beastly cards because I want more hash.

All of my rigs use multiple 7950s.  I undervolt, run a high intensity and get around 680 or better  each with very, very few stales mining LTC.

Do not use 7970s or that new 7990 which is merely two 7970s in one housing.

I have 4 and 7 card rigs running and am working on a prototype 14 card rig.

that's a lot faster than the page says here:
https://en.bitcoin.it/wiki/Mining_hardware_comparison

you're quite overclocked; what is your mhash/watt?

I would still go with some 7950s for versatility. Just make sure they can be undervolted.

My 3xSapphire OCs can do:

Scrypt 1820 kh/s - 770 W out of the wall
Scrypt 1720 kh/s - 600 W out of the wall
Scrypt 1660 kh/s - 570 W out of the wall (favorite on hot summer days)

SHA256 1720 kh/s - 530 W ouf ot the wall (clock memory down to 155 mhz, originally 1250 mhz)

since ASICs are there/coming, the point of graphics card should be the versatility.

Probably the new 7990 Malta. It has a TDP of 375W thanks to binned 7970 chips and I can get it to do 1.05 Mhash on -20 % PowerTune. -15% PowerTune it does 1.2 Mhash, and 1.35 on  0% (default).

It costs around $1050 though so not very economical. But it's one of the best performance/watt cards, possibly better than the 7790.

oops i was dumbly thinking 7750

IMHO, based on my personal experience, you are going to have to go a long way in terms of power savings to make up the difference in cost between the 7990 and a pair of 7950s.

My $.02.

I feel like buying a bunch of 7790s is so much better then buying a few 7950s.  Newegg offers 7790s for 134 after rebate with the free 3 games, so the final card price would probably be under 100.  The 7950 is 284 at newegg with the games so lets say around 240 for each card.  I can have my 7950s hashing at 550 @ 75C with power of 250ish while the 7790 hashes at a solid 250 with a power consumption of 65 watts.  Thats huge.  

8 7790s on two motherboards would pull around ~700 watts at 2000 hash rate while my 3 7950s, 1 7970 and 1 7790 can hash at ~2500 @ wattage 1215.

For BTC maybe 7790 would be better, but for scrypt mining 7950 is better due to 384-bit memory interface.

I'm mining 250 k/hash on scrypt with a 7790 @ 65 watts

When I got back into mining I went this route. I've got a 7790 and a 6670 mining away. I'll replace slower card soon with another 7790.

 :)

Which model 7790 are you using?

Power consumption is offset by speed of hash rate.

My $.02.

:)

Anyone mining with 6770? I am getting 180 khash with intensity 16.

I get at least 660 out of EACH of my 7950s and I have a lot of them!

:)

4 7950s at 630-650kh will pull less than 950w if set right ( i have 20 rigs with 4 and 1 rig with 3 cards

ahh. what motherboard(s) are you using?

croshair iv fomila with a 1090t cpu underclocked

isn't there a cheaper cpu?

i spent 130 more per rig so i have a beter resale value ( saphire vapor x gpu's croshair iv motherboards and 1090t cpu and ax1200 psu) i have found that cheap parts dont last long and resell for next to nothing