Upgrading from dual 6870s?

[humanage]

I have two 6870s and about $300 CAD to spend. The relevant features are my mining rig are 2 PCI-E x16 slots and a OCZ ZT 700 Watt PSU. I'm currently squeezing 651MH/s on the rig, but want more mining power.
My questions are:
1. Would upgrading to 2 5870s be worth it(spending about $150)(they produce mininum 400MH/s each vs my 6870s at 225.5MH/s each)?
2. Would my PSU handle to overclocked 5870's, if not, would a Cougar CMX 700 Watt(from Gaming pc)?
3. Does anyone have a better recommendation for a Mining upgrade?

[John (John K.)]

For me, I would upgrade the board to one that has more PCIE slots so that you could maximize your mining cards. I currently mine using a three card setups of 5850's and a 5870, and have space for another card too. Remember that for mining, PCIE x4's would do too.

[humanage]

For me, I would upgrade the board to one that has more PCIE slots so that you could maximize your mining cards. I currently mine using a three card setups of 5850's and a 5870, and have space for another card too. Remember that for mining, PCIE x4's would do too.

That would mean I'd have to spend another $240+ of an 1155 mobo(1155 system here). I don't feel like doing that, no performance upgrade.
Anyways, I now have a bit over $300, and if I sell at least one of my 6870s($140 minimum) to make room, I'll have over $440 CAD, or $580 if I sell both cards. What should I upgrade to GPU wise? 5870 a good idea?

[jake262144]

A good idea. An even better one would be going with the top-of-the-line mining card, the 5970.

[humanage]

A good idea. An even better one would be going with the top-of-the-line mining card, the 5970.

Hmm, I'll see what I can find on eBay. I guess it would be better as I would have a free PCI-E slot. Would my OCZ 700 PSU be able to handle and overclocked 5970 and 6870 though?

[jake262144]

The OCZ ZT 750 is a very decent PSU. Bronze certified, fully modular unit, is this the one?
According to the load table, it can deliver up to 744 Watts on the 12V rail. I estimate the total PSU load at no more than 500W. It should run just fine.
The energy consumption will be even smaller if you underclock the memory. You know that memory speed can be lowered to 150..300MHz on most cards without affecting the hashing speed, right?

[Arnold2222]

I have two 6870s and about $300 CAD to spend. The relevant features are my mining rig are 2 PCI-E x16 slots and a OCZ ZT 700 Watt PSU. I'm currently squeezing 651MH/s on the rig, but want more mining power.
My questions are:
1. Would upgrading to 2 5870s be worth it(spending about $150)(they produce mininum 400MH/s each vs my 6870s at 225.5MH/s each)?
2. Would my PSU handle to overclocked 5870's, if not, would a Cougar CMX 700 Watt(from Gaming pc)?
3. Does anyone have a better recommendation for a Mining upgrade?

1. hmm i am getting up to 335Mhs on my 6870, maybe is worth to check configuration or other mining soft ? try cgminer 2.2.1 and drivers 11.6a you should get better Mhs or there is just mistake and should be 325 as i see you have 651 for both ?

[humanage]

Mistake, sorry. I screwed up my drivers yesterday though. Trying 11.1a now with cgminer. 275MH/s. Gonna do 11.6a when I come home from work, as you recommend.

[DeathAndTaxes]

5970 w/ underclocked memory pulls about 230W DC.  It isn't as power hungry as people think.  If you have a kill-a-watt you could measure your load w/ only 1 card.  Remember power measured is AC.  The DC load is going to be 10% to 15% less.

I wouldn't get 5870 because you won't gain that much.  If you are limited to 2 card and unwilling to change boards then 5970 is likely your only useful solution.

The bad news is price of used 5970 is rising.  In Dec it was <$300 per card.  In early January more like $300-$350.  Now it is $350 to $400.  If you watch patiently you probably could grab one for $350.  You can sell the existing cards to put money towards a second one.

A single 5970 will get you ~730 to ~760 MH/s.  A pair puts you in the ~1.4 to 1.5 GH/s range.  One 5970 is fine but you need to check your PSU for 2.  2x 5970 will need 2x 6 pin connector & 2x 8 pin connector.  The PSU will be heavily loaded but it should be fine.  People saying to only load PSU to 50% are just passing on urban legends.  Modern PSU can handle higher loads.  Still it will be close, the best thing would be to measure your current load @ idle.  If you can't do that provide the non-GPU specs of your system the system idle load can be estimated.

[KoKos]

You need to up your clocks. i have a 6850 running at 260mhash and i know a 6870 should do almost 300. make sure you use phoenix phatk and correct flags

[Eisenhower34]

Question remains for me why you invest money at the moment when the new ati 7000 series comming soon?

[DeathAndTaxes]

Question remains for me why you invest money at the moment when the new ati 7000 series comming soon?

Because he bought a used GPU at less than the price of any 7000 series on MH/$ basis. 

[Eisenhower34]

You will still think the same when you can make 4000 Mhashes with one of the 7000 series?

I cannot predict how good or bad the new cards will be, but I wouldnt risk to lose money because there WILL be a price drop when those babys come out in 2 weeks.

But im just a noob who cannot leave the noobi section till he has wasted 4h of his life waiting for this status to disappear...

[DeathAndTaxes]

You will still think the same when you can make 4000 Mhashes with one of the 7000 series?

I cannot predict how good or bad the new cards will be, but I wouldnt risk to lose money because there WILL be a price drop when those babys come out in 2 weeks.

But im just a noob who cannot leave the noobi section till he has wasted 4h of his life waiting for this status to disappear...

The 7950 & 7970 are already out and ... they aren't anywhere close to 4000 MH/s.  LOLZ. The 5870/5970 are still two of the best miners available.   They likely will only be dethroned by the 7990 and then at $850 a pop.

[humanage]

Because he bought a used GPU at less than the price of any 7000 series on MH/$ basis. 

[/quote]
Yep, $140 per card off my friend.

[Eisenhower34]

The 7950 & 7970 are already out and ... they aren't anywhere close to 4000 MH/s.  LOLZ. 5970 is the fastest card in the world.  It will only be dethroned by the 7990 and then at $850 a pop.

Looool I really missed the release of those babys ^^ Looks like im not up to date. Wasted too much time with my physics (electrons / protons, not sports) studies.