Upgrade or crossfire hd7970?

[jimhaumman]

Hi guys.
I'm thinking which way to go to upgrade my PC.
The cheapest way is to buy second HD7970/280X,which will give me nice boost in fps in games where crossfire is supported.
I've got asrock z77 extreme 4 (2 x PCIe 3.0 x16 Slots) and BeQuiet Dark Pro 750W,so no bottleneck and should be enough juice to run it.How much can single card on 1,2 mv with 1100mhz and 1600 mhz draw from the wall?
Not so sure with i5 3570k,will I see constant use of 99% on both cards?
What with myths about i7 that is better for crossfire/sli (battlefield 3 HT and all that).
What with games which have heavy cpu usage: Crysis 3?How much will I need to OC cpu to get 99% usage on 2xgpu,is stock not enough?
I'm not worried at all about temps and cards throttling cos they will run underwater.
How much for second hand cards(hd7970,280x) go in MM?I'm not quite there yet nut would be nice to have a clue
ta

 

[nutsnut]

Around £150~£175 on the MM. On games that like cpu cores/threads you may be a little bottlenecked by the cpu but not by much and you will still see a nice performance boost.

 

[jimhaumman]

"On games that like cpu cores/threads you may be a little bottlenecked by the cpu"-would i7 3770k improve that in this cases,or i5 3570k OC to 4,8 Ghz would be enough?
What I might do is buy second hand i7 3770k and sell i5 3570k,but I want to now if is worth it.I know for sure that I would see nice boost in synthetic benchmarks (physic score) but i don't care about,I would need to see boost in games.

 

[Uncle Petey]

Hi guys.
I'm thinking which way to go to upgrade my PC.
The cheapest way is to buy second HD7970/280X,which will give me nice boost in fps in games where crossfire is supported.
I've got asrock z77 extreme 4 (2 x PCIe 3.0 x16 Slots) and BeQuiet Dark Pro 750W,so no bottleneck and should be enough juice to run it.How much can single card on 1,2 mv with 1100mhz and 1600 mhz draw from the wall?
Your psu will be fine for almost anything except 1.3v OC's in Sleeping Dogs benchmark using two cards. The total draw would obviously also depend on your cpu clocks/volts etc.

Not so sure with i5 3570k, will I see constant use of 99% on both cards?
Depends on the game.

What with myths about i7 that is better for crossfire/sli (battlefield 3 HT and all that).
True, in games like BF3/4 (dunno where mantle leaves this tbh) and Crysis 3. For a lot of other games, not so much.

What with games which have heavy cpu usage: Crysis 3?How much will I need to OC cpu to get 99% usage on 2xgpu,is stock not enough?
Dunno, but I have my 2600K @4.7 + 7970's @1200/1600 and they get 99-100% usage.

Spoiler

Very High / 4xMSAA

I'm not worried at all about temps and cards throttling cos they will run underwater.
Excellent

 

[jimhaumman]

Cheers Uncle Petey,you're the man I got more question for.
I google it,and there is a lot threads,Battlefield 3 HT off.
In Crysis 3 HT helps:
http://i.imgur.com/ZYLY0xK.png
But there is more to that,people are disabling HT cos it adds 8-10C to cpu temp.,so it means lower OC,when HT is off you're getting i5 with bigger memory cache,and faster clock speed (stock values cpu)

 

[Uncle Petey]

I thought they sorted out the BF3 HT problem ages ago. Could be wrong...
BF4 definitely likes a bit of HT with dual cards though. Again, not sure where Mantle comes into it here.

 

[jimhaumman]

Could you check for me in Crysis 3 with HT off,usage of your gpu,please?,also if you see lower fps?
sandy vs ivy clock for clock is roughly 10% faster.
My current gpu OC only to 1100/1600mhz on 1,75 mv,so I won't go here than that in crossfire with other card,so my psu should be fine.

 

[Uncle Petey]

Just tried it and it all looks the same in term of usage and fps. Go figure...

ED: I will say that I tested in the same spot as the screenshot I posted. There are other areas of the game that are more cpu/thread intensive such as the long grass bits.

 

[jimhaumman]

I bought MSI R7970 Twin Frozr 3GD5/OC BE for 124 quid with 22 months warranty left,card should be with me next week.
Then I see how i5 3570k OC to 4,5 is doing in this setup.

 

[jimhaumman]

Strange thing happens to the second card when I restart computer.Fans starts to spin 100% and then later in windows CCC doesn't see the card ( gpu-z,afterburner as well),when I restart computer and go to mobo bios the is no card showing in pci-e slot.
So back to windows switch off computer.
Switch on pc and the card is back.
I'm on 14.6.Any ideas?

 

[P4Clock]

Start by cheacking your power plugs, i know it sounds silly but a bad connection would make this happen