ATI radeon HD 5770 & 5750

The last 30 days have seen a ton of new technology, from Intel’s Lynnfield-based Core i5 and Core i7 processors (which we reviewed here, tested in a number of different games with CrossFire and SLI setups here, and measured the effect of integrated PCI Express 2.0 right here) to ATI’s Cypress graphics processor (manifest through the Radeon HD 5870 and Radeon HD 5850). Between those launch stories, I’ve run thousands of benchmark numbers and written tens of thousands of words. Thus, when I sat down to write this Radeon HD 5770/5750 review (after running another 500+ tests), I had to mix it up a bit and have a little fun with the intro. Feel free to read while listening to Biz Markie’s Just A Friend.

Have you ever seen a card that you wanted to buy?
Killer performance, but a price sky-high?
Let me tell you a story of my situation;
I game on PCs, forget Playstation.
The tech that I like is really high-end.
But I gotta get by with a couple Benjamins.
I upgrade once a year, whenever I can.
Processors, hard drives, graphics cards, RAM.
i7 looked great; I bought i5.
Now it’s time for new graphics; make my games look live.
I know of Nvidia; I know ATI.
So many boards between ‘em, makes me want to cry.
G92’s been around
, and that’s a fact.
Couldn’t find 740
; that launch was whack.
But I’ve pulled out my wallet out and I’m ready to buy.
I want something new; no shrunken die.
Read Chris’ Cypress story
; that card looked hot
If I had four bones, it’d already be bought.

Come onnnnnn, I can’t even afford that.
I’m looking for something under $200, man.

And here’s where ATI chimes in…

We’ve…we’ve got what you need. And you say you have $160 to spend?
And you say you have $160 to spend? Oh gamer…
We’ve…we’ve got what you need. And you say you have $160 to spend?
And you say you have $160 to spend? Oh gamer…
We’ve…we’ve got what you need. And you say you have $160 to spend?
And you say you have $160 to spend?

Last Year’s Flagship Is This Year’s Mid-Range

Meet the Radeon HD 5770...

If the Radeon HD 5870 was characterized by roughly twice the computing resources as Radeon HD 4870, then the Radeon HD 5770 represents a halving of Radeon HD 5870. You’d think that’d yield something that looks a lot like the Radeon HD 4870 to which you’re already accustomed—and you’d be close to correct.

The Radeon HD 4870 is based on ATI’s 55nm RV770, sporting 956 million transistors on a 260 square millimeter die. It boasts 800 ALUs (shader processors), 40 texture units, a 256-bit memory interface armed with GDDR5 memory (cranking out 115.2 GB/s), and a depth/stencil rate of 64 pixels per clock.

...and the Radeon HD 5750

In contrast, ATI’s 40nm Juniper GPU is made up of 1.04 billion transistors. It also wields 800 shader processors, 40 texture units, and a depth/stencil rate of 64 pixels per clock. But its memory interface, being a halved version of Cypress,’ is only 128-bits wide. Nevertheless, ATI arms it with GDDR5 memory able to move up to 76.8 GB/s.

Right off the bat, we knew that this was going to be a very tough comparison—not only between ATI and Nvidia, but also between ATI and its own lineup of products. Yes, both of these new cards leverage DirectX 11 support. They both offer three digital display outputs split between DVI, HDMI, and DisplayPort connectors. And the pair is able to bitstream Dolby TrueHD and DTS-HD Master Audio from your home theater PC to your compatible receiver via HDMI 1.3, too.

But with specs that look roughly on par with the Radeon HD 4870 and Radeon HD 4770, anyone who recently purchased one of those previous-generation boards is bound to feel smug about the performance we see in this write-up—at least until DirectX 11 applications start emerging in greater numbers.

So, what’s the verdict? Is the Radeon HD 5770 worth paying $160 for amongst $145 Radeon HD 4870s? Is the 1GB Radeon HD 5750 worth its $129 price tag in comparison to the $120 Radeon HD 4770 (with 512MB) or even Nvidia’s GeForce GTS 250 at a similar price? Let’s dig into the speeds, feeds, numbers, and multimedia tests for more.

ATI’s Radeon HD 5770 And 5750

There’s really no need to rehash all of the architectural elements that comprise the Radeon HD 5770 and 5750—if you want to know more about how ATI improved this generation’s architecture over RV770, check out our original Radeon HD 5870 review. When I say that the Radeon HD 5770 is half of that flagship, I’m being literal.

As mentioned, the Juniper GPU consists of 1.04 billion transistors (to Cypress’ 2.15 billion). It sports 800 ALUs (to Cypress’ 1,600). It leverages 40 texture units (to Cypress’ 80). It boasts 16 ROPs (to Cypress’ 32). I think you get the picture here. If not, a die block diagram comparison should do the trick:

Mid-Range: Juniper High-End: Cypress

Even the speeds and feeds work out comparatively. Radeon HD 5870 employs 1GB of GDDR5 memory running at 1,200 MHz, delivering 153.6 GB/s. The Radeon HD 5770 also sports 1GB of GDDR5 at 1,200 MHz, serving up 76.8 GB/s. Eight hundred “shader processors” times 850 MHz times two gives the Radeon HD 5770 1.36 TFLOPS of compute power, versus the 5870’s 1,600 * 850 MHz * 2 = 2.72 TFLOPS.

Radeon HD 5770 Radeon HD 5750 Radeon HD 4870
Compute Performance 1.36 TFLOPS 1.008 TFLOPS 1.2 TFLOPS
Transistors 1.04 billion 1.04 billion .956 billion
Memory Bandwidth 76.8 GB/s 73.6 GB/s 115 GB/s
AA Resolve 64 64 64
Z/Stencil 64 64 64
Texture Units 40 36 40
Shader (ALUs) 800 720 800
Idle Board Power 18W 16W 90W
Active Board Power 108W 86W 160W

Thus, all of the same architectural balancing that went into the Radeon HD 5870 should carry over here, and we should see a performance picture as good or better than what ATI’s Radeon HD 4870 was able to do, given its 800 shader processors at 750 MHz (totaling 1.2 TFLOPS)and GDDR5 memory running at 900 MHz.

Oh, but there’s a rub. The Radeon HD 4870 also employed a 256-bit bus, giving it 115.2 GB/s of memory bandwidth. We’ll have to see how that notably different specification affects the overall performance picture. If there’s an Achilles’s heel that causes the 5770 to stumble, that will be it.

The Radeon HD 5750 centers on the same Juniper GPU as its big brother. ATI disables one of the chip’s 10 SIMD cores, switching off 80 ALUs and four texture units. The processor’s core clock is then decelerated to 700 MHz, yielding a nice round 1 TFLOPS of compute muscle. ATI doesn’t mess with the GPU’s back-end, so you still get 16 ROPs and a 128-bit memory bus loaded with 1GB of GDDR5 memory. However, the clocks there are slightly lower too, yielding 73.6 GB/s from the 1,150 MHz RAM.

The Boards

The Radeon HD 5770 itself is shorter than the Radeon HD 5850, which was already shorter than the behemoth Radeon HD 5870. At 8.5” (an inch less than the 5850), it’s a very chassis-friendly card.

As with the larger Cypress board, the 5770 employs rear-mounted auxiliary power, though it only needs one connector instead of two. Further, ATI recesses the plug a bit, so protruding cables are less likely to get in the way.

Back of the Radeon HD 5770

We were already blown away by ATI’s efforts to minimize power consumption with the Radeon HD 5870 and 5850. However, the smaller Juniper die is even more miserly. At idle, the Radeon HD 5770 is rated at just 18W (down from the 5850’s 27W and the 4870’s ravenous 90W). Under load, the Radeon HD 5770 uses just 108W (versus the 5850’s 151W). Already you can see how this might be the world’s most perfect HTPC card. But wait…there’s more.

ATI’s Radeon HD 5850 sports an entirely different design. Up until now, all of the 5000-series cards have featured enclosed shrouds with blower-type coolers that exhaust air from a vent on each card’s I/O bracket. The Radeon HD 5750 sports a simpler dual-slot heatsink/fan combination. The PCB is shorter still at 7.25,” and it likewise comes equipped with a single auxiliary power connector.

Back of the Radeon HD 5750

This could be an even better solution for big-screen gamers and theater enthusiasts. Lower clocks and a simpler cooling implementation mean a slightly more conservative 16W idle footprint, and a load requirement of up to 86W. As we’ll see in the benchmarks, this is no speed demon (at the risk of ruining several pages worth of data, it’s a bit quicker than a Radeon HD 4770); however, you’ll find that’s often enough to play at 1920×1080. And the addition of Eyefinity/bitstreaming really makes the 5750 a shoo-in for quiet environments in need of performance and better functionality.


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