CrossfireX vs SLIQuad

[laywill]

Thanks to everyone!

I was totally unaware of the fact that a 295 is a set of paired 260GTX cards! That explains why an i7 with 4 HD4890 cards blow the i7s paired with 295GTX cards out of the water.

I had a look at the top results for 3DMark Vantage on hwbot.org here. The top two results use both different CPUs and different GPUs. The holder of the highest score has an i7 920 @ 4GHz on water cooling with a pair of 295GTX cards and scored 32270 marks. Second place used a Xeon W3570 @ 5.2GHz on Ln2 combined with 4 HD4890s.

If, as has been suggested earlier, the 295s in SLI are less powerful than 4 HD4890s in x-fire, and that most benchmarks with multiple GPUs end up CPU bound, why has a 4GHz i7 with nVidia GFX triumphed over the higher clocked Xeon with the 4890s?

I know that AMD have been pushing the dragon platform (Phenom + 790GX mobo + HD4870) and are soon to be releasing an updated version (codename Leo?) with support for higher clocked DDR3 RAM or something along those lines. However, Phenoms do not compare to an i7 or a Xeon so are totally useless for a record attempt.

Have I just gone and confused the whole issue here? As far as I now see it: 295GTX cards are great in single card setups; for multi GPU setups go for HD4890s because of higher performance and a big saving for the piggy bank. So is there a huge difference, which is affecting the performance results, between an i7 and a Xeon W3570?

Thanks again for everybody's help o far in sorting a muddled mind

[sammorris]

Yeah, the GPUs are slightly modified, but GTX275s they ain't (the 295 came out before the 275 I think) - the other issue is that in high memory environments (mostly 2560x1600) the GTX295's 896MB per GPU of memory coupled with nvidia's weaker memory management means AA performance is very unpredictable. Four 1GB HD4890s are a more powerful and sustainable combination, IF you can find a motherboard that will fit four dual slot cards, they are very few and far between. The only board I've found designed straight-up for the job is an old MSI Phenom board.

I wouldn't worry yourself with 3dmarks. The HD4870 and GTX260 are rough equals yet the GTX260 absolutely demolishes the 4870 in 3dmark, remember nvidia have about 10 years of driver coding to abuse 3dmark for unrealistically high scores. Look at real-world benchmarks, since you aren't going to be playing 3dmark!

To be honest, I never advocated GTX295s. A pair of 4890s, or even a 4870X2 were a better buy IMO due to the lower price, and more consistent performance.

[kalniel]

I was totally unaware of the fact that a 295 is a set of paired 260GTX cards!

They're not - they're paired 275s, which when released as single cards could be clocked higher.

Have I just gone and confused the whole issue here? As far as I now see it: 295GTX cards are great in single card setups; for multi GPU setups go for HD4890s because of higher performance and a big saving for the piggy bank. So is there a huge difference, which is affecting the performance results, between an i7 and a Xeon W3570?

Natively? Not all that much, but when overclocked I don't think the only thing they are adjusting is CPU frequency..

If you want a pair of GPUs then get a single 295. If you want triple GPUs then get 3x4890. Anything else is going to be CPU or subsystem limited unless you take extreme measures to work around those.

[laywill]

Thanks for the advice!
Cheers everybody.

[Terbinator]

Yeah, the GPUs are slightly modified, but GTX275s they ain't (the 295 came out before the 275 I think)

It has the same amount of SP's per GPU as the 275 (240) albeit it clocked at the 260 references, so id still say it has more in common to the 275 than the 260

Edit: Would dual-socket motherboards help relieve the bottleneck ?

[kalniel]

Edit: Would dual-socket motherboards help relieve the bottleneck ?

Not by themselves.

You need:
1) An application that has an efficient and multi-CPU and GPU core scaleable graphics rendering pipeline.
2) An API that is efficient and multi- CPU and GPU core scaleable.
3) Non-limiting connections from GPU-GPU, CPU-CPU and GPU-CPU.
4) Non-limiting CPUs.
5) Non-limited GPUs.

Drivers have only recently started becoming multi-CPU core aware. DirectX11 will bring some awareness to the windows API.

[sammorris]

I'm pretty certain they're paired 260s, because two 275s in SLI give a 295 a noticeable beating. If you want a pair of GPUs, buy a pair of HD4890s. if you want three GPUs, buy three 4890s. I think you can see where this is going. Were GTX275s reasonably priced, I would recommend them instead. The ridiculous cost of a GTX295 means it is never going to be worth it in the face of the 4890s.
This "bottleneck" only really applies to 3dmark. In real world applications you're not going to see it as often unless you're using pointlessly low detail for the graphics setup you're using. (For ref, 3dmark will only see the extra cores of a dual CPU system in the CPU tests, the graphics tests will be unaffected).

[kalniel]

I'm pretty certain they're paired 260s, because two 275s in SLI give a 295 a noticeable beating.

Even if you clock the 295 chips up to an equivalent clockspeed?

[CAT-THE-FIFTH]

The thing is though the HD4890 and HD4870X2 are just better value for most people ATM.However the GTX275 is starting to drop in price nearer to the overclocked HD4890 cards though. Crossfire is better supported on BOTH Intel and AMD platforms and the motherboards tend to be cheaper too. However it seems that HD4870X2 cards are in very short supply now - perhaps production has been wound down in anticipation of the new DX11 parts??

TBH,a single reference clocked HD4890 will run most current games at decent setting at 1680x1050 and even 1920x1200 which is not bad for a graphics card under £150.

[sammorris]

kalniel: Even if you clock the 295 up to an equivalent clock speed, two 275s still beat it, sometimes by up to 10%.
Cat: The HD4870X2 is unfortunately irrelevant as it no longer exists (was discontinued at source by ATI at beginning of July), HD4890s are all we have to play with until the HD5870s come out for the moment.

[nibbler]

When DX11 gpu's come out there will be a dual GPU...
lets see how that compares. I've heard stories that quad ATIs see terrible performance in games but who knows, depends on the game I guess.

[sammorris]

As someone who uses Quad CF I assure you it's not the case. trouble is, the system was invented before the drivers for it were any good, so most reviews were published back when it genuinely was rubbish. Look at any recent reviews and it fares much better.
Historically, the dual card for a generation does not come out as early as the solo counterpart so we'll have to see what happens. Of course with the HD4870 it was only a month after that the X2 arrived. Here's hoping the same applies to the HD5870.

[nibbler]

As someone who uses Quad CF I assure you it's not the case. trouble is, the system was invented before the drivers for it were any good, so most reviews were published back when it genuinely was rubbish. Look at any recent reviews and it fares much better.
Historically, the dual card for a generation does not come out as early as the solo counterpart so we'll have to see what happens. Of course with the HD4870 it was only a month after that the X2 arrived. Here's hoping the same applies to the HD5870.

Interesting. Nice system you got there then
So it will be the 5 series and carry on with the 58 55 57 series etc like the 4000 series?

[CAT-THE-FIFTH]

I had a rumour that the new ATI cards were going to be called the "7 series" although this could be not true.

[sammorris]

As far as I can see they will have the same sort of system, but the HD5870 name has not come from ATI themselves, there is no official name. HD5870 is the most likely, but there is no concrete evidence to support that yet, a little unusual given the product is only 3 weeks away.

[nibbler]

As far as I can see they will have the same sort of system, but the HD5870 name has not come from ATI themselves, there is no official name. HD5870 is the most likely, but there is no concrete evidence to support that yet, a little unusual given the product is only 3 weeks away.

I reckon it's gonna muck up my plans to buy a 4890 in december even more