crossfire 7870 or 7970?

flash2021 · Jul 30, 2012

All,
I have a pretty good HIS IceQ 7870 ghz edition graphics card right now, and want to get more power! so here are some questions

1. how would getting a second 7870 (brand TBD) compare to say, selling my 7870 and getting ONE 7970?
2. if I crossfire, is my Antec 620W power supply enough? (standard setup, see rig in my sig, 1 monitor (might upgrade to 2)
3. If I crossfire, will the faster card be downscaled to perform at the slower cards Mhz for cpu/mem freqs? (I've done some research and have have seen conflicting statements)
3a. if not, what is the BEST 7870 card on the market now, especially for OC'ing? the gigabyte or sapphire perhaps?

thanks for y'alls feedback in advance!

PureBlackFire · Jul 30, 2012

Quote:

Originally Posted by flash2021

All,
I have a pretty good HIS IceQ 7870 ghz edition graphics card right now, and want to get more power! so here are some questions

1. how would getting a second 7870 (brand TBD) compare to say, selling my 7870 and getting ONE 7970?

a 7870 crossfire setup would be much faster than a single 7970.
Quote:

2. if I crossfire, is my Antec 620W power supply enough? (standard setup, see rig in my sig, 1 monitor (might upgrade to 2)

your psu is easily enough
Quote:

3. If I crossfire, will the faster card be downscaled to perform at the slower cards Mhz for cpu/mem freqs? (I've done some research and have have seen conflicting statements)
3a. if not, what is the BEST 7870 card on the market now, especially for OC'ing? the gigabyte or sapphire perhaps?

don't know for sure. my last cf setup has two 6870's, one I ran at 970mhz core and the other at 100mhz, but I eventually ran them both at 970mhz. I often here conflicting reports on this too.
Quote:

thanks for y'alls feedback in advance!

no problem

googleberry · Jul 30, 2012

From what I've read about Crossfiring, the faster card will not be "automatically down-clocked" to the slower cards speed. Meaning that if you get a faster card (in a perfect scaling situation), you would see more than double the performance than that of the slow card. Does that make sense?

For example, you can crossfire a 7850 and a 7870. By doing so, the 7870 will not just become a 7850... According to what I've read, the performance will be somewhere between the two cards. I know this isn't exactly the same, but is still similar.

raghu78 · Jul 31, 2012

OP for a single 1080p monitor a HD 7950 OC is enough. Your sig rig shows a Asus VS248 1080p monitor. Get a HD 7950 OC. overclock it to 1.15 Ghz and you will be easily 30% faster than HD 7870 (1250 Mhz)

http://www.anandtech.com/show/5476/amd-radeon-7950-review/18

http://www.anandtech.com/show/5625/amd-radeon-hd-7870-ghz-edition-radeon-hd-7850-review-rounding-out-southern-islands/19

Crysis Warhead 1920 x 1200 Enthusiast 4x AA

HD 7950 (1050) - 57.1
HD 7870(1200) - 45

Metro 2033 1920 x 1200 Very High AAA

HD 7950 (1050) - 63
HD 7870(1200) - 50

Batman AC 1920 x 1200 Extreme 4x AA
HD 7950 (1050) - 88
HD 7870 (1200) - 66

here is a voltage overclocked HD 7950 OC compared with a HD 7970 (925 Mhz)

http://www.hardocp.com/article/2012/03/01/xfx_radeon_hd_7950_black_edition_video_card_review/8

You should get around USD 240 after selling the HD 7870 (because a new HD 7870 can be had for USD 260 after rebates).

here is a user running the sapphire hd 7950 950 mhz edition. overclocked comparisons between GTX 670(1268) and HD 7950 (1100) in Heaven, Dirt 3 show they perform similar.

http://www.overclock.net/t/1196856/official-amd-radeon-hd-7950-7970-owners-thread/13790#post_17796906

here are a few good options

http://www.newegg.com/Product/Product.aspx?Item=N82E16814127667
http://www.newegg.com/Product/Product.aspx?Item=N82E16814125414
http://www.newegg.com/Product/Product.aspx?Item=N82E16814102991

Darkchild · Oct 7, 2012

Honestly why buy a new 7950 when he already has the 7870 there not that different in performance to justify trying to sell then buy?
First he has to find a buyer for the 7870, pay to ship it if buyer isnt local ,and then he might not get what he wants for it
So its easier to just throw a second 7870 in and call it a day
not to mention settling for 30% more performance when almost double that can be had cheaper sounds silly even on a single 1080p

broadbandaddict · Oct 7, 2012

If I were you I would crossfire the existing 7870 with another.

Bruennis · Oct 7, 2012

If I were in your shoes, I'd get this card http://www.newegg.com/Product/Product.aspx?Item=N82E16814127681. In my opinion, this is one of the best if not the best Pitcairn card. It tied for best overclocker in the review below.

http://www.techpowerup.com/reviews/MSI/HD_7870_HAWK/31.html

On any given single monitor resolution and at 1260MHz/1600MHz; a 7870 would match OR beat a stock 7950 and in some scenarios even a lightly overclocked OR factory overclocked 7950. In crossfire, no current single-chip GPU will match the duo not even my Lightning 680 @ ~1400MHz/~1700MHz. The link below is review of Hawk 7870 crossfire. Check it out

http://www.pcper.com/reviews/Graphics-Cards/MSI-R7870-HAWK-Review-and-CrossFire-Performance-AMD-HD-7870-Steroids

The Hawk 7870 in PCPER review was able to reach 1300MHz/1450MHz and so both reviews should give you a good idea of just what you can achieve with this particular card.

crossfire 7870 or 7970?

flash2021

PureBlackFire

googleberry

raghu78

Darkchild

broadbandaddict

Bruennis

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