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Your input on 4770 Crossfire System

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June 9, 2009 4:49:34 AM

Hey all,

I am about to order the parts for a new low-mid range gaming PC. Based on the great reviews for crossfired 4770's and my limited budget, it seems perfect for me since I can buy one 4770 now and the other later. I just wanted your guys input on how these would play with the rest of my system build. Please point out any bad choices I may have made. Thanks a lot in advance!

ASUS M4A78 Plus Mobo
AMD Phenom II x4 940
Crossfired radeon 4770's
4gb G.Skill Ram
500gb WD Hard Drive
400W PSU

A couple Questions:

I didnt want to buy a new power supply since I have a 400w in decent shape. But will I need more wattage to crossfire? Can I use it temporarily while I only have one 4770?

I am also considering the AMD Phenom II X2 550 Black Edition instead of the X4 since it is 80 bucks cheaper. Im looking for the best value possible. Any ideas on how much of a performance drop I will get from the x4 to the x2? Remember this is primarily a gaming pc.

Your input and expertise is greatly appreciated
June 9, 2009 5:34:24 AM

Could go for the M4A78-E (which has the aforementioned 790GX northbridge). Also of importance, it has the SB750 southbridge, which allows a PhII 940 to be overclocked very effectively.
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June 9, 2009 6:01:15 AM

As far as ram goes, Look for DDR2-1066, as the AMD chips see a significant boost from the extra ram speed.

The Phenom II X2 wouldn't be bad, but wouldn't be great either. It kinda depends on what games you play. Some games make very good use of multiple cores, many don't. I personally would go for the PII 940 if you want to build a Quad core gamer, otherwise for dual cores, I would go with an E5200 or E8400, depending on how much you can spend. Intel chips are faster clock for clock and overclock better.

Good luck finding a pair of 4770's.
June 9, 2009 6:29:04 AM

xthekidx said:
That MB is not meant for crossfire, you need a 790X or 790GX chipset. Look at these:
http://www.newegg.com/Product/Product.aspx?Item=N82E168...
http://www.newegg.com/Product/ComboDealDetails.aspx?Ite...

For crossfire, you will need at least a 500w PSU from a GOOD brand. For now, you will probably be ok using the 400w as long as its not a cheapo like a rosewill or something.



According to Newegg, the M4A78 Plus does support Crossfire: "A pair of PCI-Express 2.0 x16 cards can be mounted for cutting-edge graphic power with support for CrossFireX. " What is the significance of the 790GX chipset? Why is it necessary for crossfireX?

Oh, and the power supply is from LinkWorld, is that considered crappy? (It came with my tower) Thanks for your reply.
June 9, 2009 6:33:58 AM

kevindemand said:
According to Newegg, the M4A78 Plus does support Crossfire: "A pair of PCI-Express 2.0 x16 cards can be mounted for cutting-edge graphic power with support for CrossFireX. " What is the significance of the 790GX chipset? Why is it necessary for crossfireX?

Oh, and the power supply is from LinkWorld, is that considered crappy? (It came with my tower) Thanks for your reply.

It supports crossfire at x4 link, which is low bandwidth. It will bottleneck your GPU's. The 790X/GX chipsets allow Crossfire at X8 bandwidth, which is enough for most GPU's to not be bottlenecked. The 790FX chipset allows Full X16 bandwidth, which is good if you have quadfire 4870X2's or 4850X2's. You want a 790X/790GX chipset.

Linkworld is a terrible PSU brand. I wouldn't use it with any video card. Get this, it should be enough, and you will need to get a better PSU later for your video cards anyways, so you might as well get it now:
http://www.newegg.com/Product/Product.aspx?Item=N82E168...
June 9, 2009 5:25:14 PM

The motherboard is not a good choice. Even if you get it to crossfire the uneven 16x and 4x slot will greatly hinder your performance. Consider this board instead.

ASRock A780GXE/128M $79.99
http://www.newegg.com/Product/Product.aspx?Item=N82E168...

It's the same price and while it uses the 780G chipset it splits the lanes between two 8x slots by using a switch chip, just like the old Radeon Xpress X1600 days.

As for you PSU what brand and model is it? If it's a good top tier PSU (google PSU tiers if you don't know what I'm talking about) then it will probably be O.k.. If it's a crappy PSU on the other hand then it's not really a good idea and you should go with a decent 500W unit.
June 9, 2009 8:12:40 PM

megamanx00 said:
As for you PSU what brand and model is it? If it's a good top tier PSU (google PSU tiers if you don't know what I'm talking about) then it will probably be O.k.. If it's a crappy PSU on the other hand then it's not really a good idea and you should go with a decent 500W unit.


400W Linkworld. A ticking time bomb, in other words.

kevindemand said:
the power supply is from LinkWorld, is that considered crappy? (It came with my tower)

June 12, 2009 8:30:26 PM

Hey guys, thanks for your replies. Im still having trouble nailing down a mobo that I really like. I've looked at all your suggestions, but would really like a board for under 100 bucks. What are your opinions on the Biostar Tforce TA 790GX?? It fits a phenomII, has the 790GX chipset, and is a good price.
June 12, 2009 9:26:10 PM

Haha, I just realized xthekidx had already recommended me that board. Oops. Well now I am a lot more confident in it.
June 12, 2009 9:37:35 PM

Proximon, I have thought about the X3. That is definitely a valid option. Does anyone know the major difference between a 920 X4 and a 940 X4 other than the socket? The 920 is significantly cheaper than the 940, but how does their performances compare?

Basically, which of these is the best value:

Phenom II X4 940
Phenom II X4 920
Phenom II X3 720

Thanks all
June 12, 2009 10:08:32 PM

The 940 or the 720 would be the best value there. The 920 runs at 2.8ghz vs 3ghz, and is a non BE processor, meaning its multiplier is locked. The only way to overclock the processor is by changing the bus speed, and AMD chips can be very finicky about that. FSB overclocking is much more complicated than multiplier overclocking too, since you have to worry about ram speeds and voltages as well as bus voltages in addition to processor voltage ect. The 940 is IMO the best value of those processors, however if you won't do anything that uses 4 cores you might as well go for the 720. Most games won't use more than 3 cores, there are about 2 or 3 that will actually fully utilize a quad-core CPU.
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