Which is better 2 6800gt in SLI or 1 7800gt

[DarCwuN]

Which would perform better 2 6800gt in SLI or 1 7800gt. According to a guy i know the 2 6800gt would out perform the 7800gt. Is this true.

 

[classy]

That would be true for the most part. But I doubt the performance increase would warrant the cost.

 

[kpb]

Depends on the game and resolution. Doesn't have the 6800gt but does have the 6800gs which is pretty dang close http://www.anandtech.com/video/showdoc.aspx?i=2607

At "lower" resolutions like 1600x1200 or lower it often matches or beats the 7800gt and gtx.

 

[NoStateofMind]

I wish someone would do a graph for these type posts. No offense to the OP, but You see this question come up alot about "do 2 of this equal 1 of that".

 

[DarCwuN]

what about 2 6600gt 256mb (combined to be 512mb) vs 1 7800gt 256mb. I am trying to build a new system and just trying to decide which way to go for the video card. There are just so many chioces these days. but the the 7800gt for us $300 looks very nice but the 2 6600gt with combined 512mb can be had for the same price to.

 

[kpb]

the 7800 would own the 6600 gt's. The 512mbs of ram means nothing because you have to keep 2 copies of everything.

 

[RussianSensation]

I'd go with 7800GT. EVGA has a 90-day stepup program (for G71 perhaps) and they have a card with copper heatsink that comes preoverclocked at $300. It'll be for sure faster than 2x6600GTs since 1 6800GT beats them. I don't think the price justifies getting 2x6800GS vs. 1 7800GT either.

 

[Crescent13]

Originally posted by: kpb
the 7800 would own the 6600 gt's. The 512mbs of ram means nothing because you have to keep 2 copies of everything.

QFT.

I would personally go with a 7800GT over 2 6800GT's. You get Transparency Supersampling AA, and radiosity and all.

 

[xtknight]

Originally posted by: Crescent13

Originally posted by: kpb
the 7800 would own the 6600 gt's. The 512mbs of ram means nothing because you have to keep 2 copies of everything.

QFT.

I would personally go with a 7800GT over 2 6800GT's. You get Transparency Supersampling AA, and radiosity and all.

Radiosity?

 

[DarCwuN]

ok so seems like the 7800gt is the better choice i like the eVGA one myself. now i wonder if my psu will handle the card. here is the link to my case can anybody tell me if this psu will suffice or should i buy a new one with the card.

http://aspireusa.net/product.php?pid=86&xcSID=9d4e87d9490d33e2a6121034d72fd979

 

[xtknight]

The 7800GT should work fine with that power supply, as long as the rest of your components are the typical (A64 3200+, SoundBlaster, 250GB HD, 2GB RAM, etc.) or less. I love my eVGA 7800GT, and it works just fine in my Antec NeoPower 480W. See rig below.

 

[v8envy]

Your PSU will most likely be sufficient. Aspire is by far not the most regarded PSU maker (although they do have their fans), but it's definitely no Powmax.

These power supplies don't handle poor quality incoming power well. Also, they are rated at 0C, and the efficiency and power out drop sharply as temperature increases to a more typical 30+ degrees C found in a computer case. If your incoming power is a steady 110v, don't have brownouts, and keep your equipment is nice and cool, you're good to go. If you have consumer electronics that constantly die prematurely, it's a good clue that your house power is not so great.

If this was my box with $300 video hardware in it, I'd invest in a UPS to go with that PS. A Seasonic or PC Power & Cooling PSU is cheap insurance for a video card that pricey.

Rated wattage on the PSU is only part of the equation. There are many, many cases of machines which won't POST or run stable with a '600 watt' el cheapo power which run just fine with a quality 250-350 watt PSU.

 

[Slitherythesnake]

The PSU that comes with the case that you're thinking of should be suffice for the time being. However, if you add more components to the computer or if you're planning to OC the PSU and/or GPU, I'd upgrade to a 500W.

 

[imported_Sincity]

I DO NOT believe your PSU will handle the 7800GT. You only have 18 amps on your 12v line. I believe you need a minimum of 24 amps. Not only do you need to be concerned with your total wattage, the big concern here is how many amps on your 12v rail(s).

Per Tom's Hardware: http://www.tomshardware.com/2005/12/02/vga_charts_viii/page21.html click on the chart

6800GT SLI is 2% faster than a single 7800GT
6800GT ULTRA is 9% faster than a single 7800GT

OC the 7800GT and it will be very competitive in both terms of price and performance compared to the 6800 series in SLI mode.

 

[airborne82nd]

Originally posted by: Sincity
I DO NOT believe your PSU will handle the 7800GT. You only have 18 amps on your 12v line. I believe you need a minimum of 24 amps. Not only do you need to be concerned with your total wattage, the big concern here is how many amps on your 12v rail(s).

I have a Thermaltake 480W PSU that only has 12v rail(s) and it runs my 7800 GT OC just fine even OC'ed @ 500/1.17.

I think your PSU will be just fine.

 

[deadseasquirrel]

Originally posted by: Sincity
Per Tom's Hardware: http://www.tomshardware.com/2005/12/02/vga_charts_viii/page21.html click on the chart

6800GT SLI is 2% faster than a single 7800GT
6800GT ULTRA is 9% faster than a single 7800GT

OC the 7800GT and it will be very competitive in both terms of price and performance compared to the 6800 series in SLI mode.

I'm not sure how exactly THG came to those results, and they may, in fact, be accurate depending on certain games at certain resolutions (i.e. SLI at resolutions such as 10x7 really doesn't show much improvement).
Anandtech's benchmarks show a different story for the most part:

In games such as Doom3, Splinter Cell CT, Quake4, and FEAR, the SLI GTs perform on average 30% better than a single 7800GT (FEAR is the exception with only 10% increase). The SLI GTs usually run equal to 256GTX performance.

Since this is a new build, however, I wouldn't buy SLI last gen. Just doesn't make sense unless you get an absolute killer deal.

 

[imported_Sincity]

Originally posted by: airborne82nd

Originally posted by: Sincity
I DO NOT believe your PSU will handle the 7800GT. You only have 18 amps on your 12v line. I believe you need a minimum of 24 amps. Not only do you need to be concerned with your total wattage, the big concern here is how many amps on your 12v rail(s).

I have a Thermaltake 480W PSU that only has 12v rail(s) and it runs my 7800 GT OC just fine even OC'ed @ 500/1.17.

I think your PSU will be just fine.

Every PSU has a 12v rail (some dual), 5 v rail, and a 3.3v rail. It is the amperage on the 12v rail that determines if you can use a modern GPU. That is pretty much standard from the various manufacturers of the 7800GT. I'm sure your Thermaltake has over 30 amps on it's 12v rails. Now, you can get away with a lower wattage PSU than 400 watts. Use this handy calculator: http://www.extreme.outervision.com/index.jsp It even allows overclocks (for CPU/GPU) and SLI configurations!

Take a look at BFG's requirements: http://www.bfgtech.com/7800GT_256_PCIX.html Please take a look at the "Min Sys Requirements" and you will see it is 26A and not the 24A I quoted.

 

[BFG10K]

The 6800GT SLI may be faster at 1600x1200 or less but that's about it. The 7800GT should be better in every other situation including the associated advantages of going with a single card.

 

[imported_Sincity]

Deadseasquirrel: Tom's is probably not as accurate. This was also told to me by a friend that dismissed Tom's findings. But nonetheless, the matrix does give some good indication of performance. Since BF2 is the only game I'm concerned with, why did it have a problem with SLI?