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We were able to take a peek at AMD NDA information (aimed at engineers) that details the technical features of the Kaveri APU. According to this information, Kaveri features a GDDR5 memory interface consisting of four 32-bit memory channels. This is perfectly matching the width of a GDDR5 chip which is also 32-bit. However, the memory controller has to be set up in a way so that two 32-bit channels work in tandem, half-channel use is not supported. The total width is 128-bit, so the main advantage comes from higher clock speeds of GDDR5 memory. This is in addition to the 128-bit DDR3 interface that we already know from previous APUs. Usage of DDR3 and GDDR5 is mutually exclusive.

While the information we glanced at is clearly preliminary and could be changed till the release of the chip, the focus should be less expensive GDDR5 chips with moderate clock speeds - not the 6GHz hotness you find in high-end graphics cards like GeForce GTX Titan. Specifically the document lists 800 MHz QDR and 850MHz QDR (3200MHz and 3400MHz) clocks which would result with 51.2 GB/s and 54.4 GB/s of system memory bandwidth. Compared to current 25.6 GB/s with the DDR3-1600, this is quite the performance bump. The surprises don't end there - Kaveri will support DDR3 up to 1250 MHz DDR (2500MHz) - it specifically adds 2400MHz and 2500MHz modes over Trinity, which officially supported up to 2133MHz. Nevertheless GDDR5 would provide a tangible bandwidth improvement and might be the smarter choice given that DDR3 above 1866MHz starts to get prohibitively expensive.
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Wait, so we'll start to see GDDR5 RAM chips in DDR3 format? This is going to confuse the hell out of a lot of people.

I think this would be very specific to embedded systems, where the GDDR5 will be soldered right onto the motherboard. Most likely in laptops, maybe certain ITX boards as well.

Edit: in other news, Kaveri will support PCI-E 3.0, has an extra 4 PCI-E 2.0 lanes for whatever peripherals for a direct connection to the CPU, which means it should support a crossfire/SLI setup pretty well. Any extra peripheral cards like a RAID controller or sound card won't take away lanes from the graphics cards part.
 

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I'm really interested how they will implement this. This should give a considerable boost to the apu's gpu performance.
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Usage of DDR3 and GDDR5 is mutually exclusive.
This sounds like a problem...
 

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Quote:
Originally Posted by Tsumi View Post

Wait, so we'll start to see GDDR5 RAM chips in DDR3 format? This is going to confuse the hell out of a lot of people.

I think this would be very specific to embedded systems, where the GDDR5 will be soldered right onto the motherboard. Most likely in laptops, maybe certain ITX boards as well.
Specifically the document lists 800 MHz QDR (Quadruple Data Rate) and 850MHz QDR (3200MHz and 3400MHz) clocks which would result with 51.2 GB/s and 54.4 GB/s of system.

( 3200 MHz x 32 bit ) / 8 = 12800 MB/s per channel
12800 MB/s x Quad channel = 51.2 GB/s total memory bandwidth

Kaveri APU covers the A10, A8, and A6 series of the 3rd generation APUs.
Sure they will be available as desktop CPU.
Remember this is APU, GDDR5 has probably been considered as HSA / GPGPU memory of iGPU, however system RAM they are supporting is still DDR3 with increased frequency (2500 MHz).
 

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Wait what......

You don't use GDDR memory for a x86 CPU due to the high latency killing the x86 performance.

Has AMD figured out a way to reduce memory related latency?

The PS4 is rumoured to use only GDDR5, but the system specific programming for the PS4 can offset the latency issues.
Regular Windows performance should be horrible due to regular desktop systems being dependant on a low latency memory subsystem.
 

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So does this mean we will see GDDR5 RAM sticks, GDDR5 built-in on die, or GDDR5 soldered right on a motherboard?

If it's truly FM2 compatible, I am going to assume that it has some RAM on die or something.
 

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so it's safe to assume PS4 will be running the Kaveri APU
will that mean DDR4 will be less affordable even when it becomes mainstream in ~2017?
 

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This will be like RIM RAM, not that common and short lived.
 

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Originally Posted by cdoublejj View Post

This will be like RIM RAM, not that common and short lived.
you are probably right for custom PC
but considering it's part of PS4...and likely the xbox and steam box....this might just become the next big thing.
 

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Originally Posted by twitchyzero View Post

so it's safe to assume PS4 will be running the Kaveri APU
will that mean DDR4 will be less affordable even when it becomes mainstream in ~2017?
No, the PS4 runs a modified Jaguar with 8 cores and a GPU that is way bigger than anything you should expect to see with Jaguar products sold to end users.
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Originally Posted by M3T4LM4N222 View Post

So does this mean we will see GDDR5 RAM sticks, GDDR5 built-in on die, or GDDR5 soldered right on a motherboard?

If it's truly FM2 compatible, I am going to assume that it has some RAM on die or something.
My first thought was, hey just like the old 880G motherboards, slap some memory for the GPU on the motherboard, but the article claims they are mutually exclusive aka. You can only run with one type of memory at the time.

This may be for OEM manufacturers or tablets, I doubt AMD can create a end user sale model for GDDR5 sticks, simply due to the market size of the company and the high price it would end up having.
 

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Quote:
Originally Posted by sumitlian View Post

Specifically the document lists 800 MHz QDR (Quadruple Data Rate) and 850MHz QDR (3200MHz and 3400MHz) clocks which would result with 51.2 GB/s and 54.4 GB/s of system.

( 3200 MHz x 32 bit ) / 8 = 12800 MB/s per channel
12800 MB/s x Quad channel = 51.2 GB/s total memory bandwidth

Kaveri APU covers the A10, A8, and A6 series of the 3rd generation APUs.
Sure they will be available as desktop CPU.
Remember this is APU, GDDR5 has probably been considered as HSA / GPGPU memory of iGPU, however system RAM they are supporting is still DDR3 with increased frequency (2500 MHz).
What does data rate have anything to do with what I said?

Kaveri + GDDR5 will probably only see limited use in embedded systems like tablets and laptops, and possibly ITX. I know full well that Kaveri will be available on desktops with DDR3, since it is FM2.
 

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Originally Posted by Flamingo View Post

What does this mean for the FM2 platform? Or is it going to be AMD's 3rd platform?
Not much, there is almost no chance that there will be gddr5 ram sticks, and probably the gddr chips will be soldered on motherboards with no ddr3 slots, maybe the cpus will be soldered also (pure speculation).
 

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So...No upgrade to Kaveri if you have an FM 2 board, or is there some sort of clever trick that they're going to do and are just not telling anyone about?
 

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Originally Posted by Kasp1js View Post

Not much, there is almost no chance that there will be gddr5 ram sticks, and probably the gddr chips will be soldered on motherboards with no ddr3 slots, maybe the cpus will be soldered also (pure speculation).
Something like the sideport memory they used to fit on a few GX / GM, MBs perhaps ¿
I wonder if this will Hybrid X-fire with the 77XX cards ?
 

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Even if they used it like sideport memory, that would surely exclude anyone with a current FM2 board. Which would be kind of sad.
 

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Originally Posted by Jared2608 View Post

So...No upgrade to Kaveri if you have an FM 2 board, or is there some sort of clever trick that they're going to do and are just not telling anyone about?
No, this will probably be only seen in certain laptops and tablets. Maybe some embedded systems as well (BGA low-end ITX boards).
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Originally Posted by mr soft View Post

Something like the sideport memory they used to fit on a few GX / GM, MBs perhaps ¿
I wonder if this will Hybrid X-fire with the 77XX cards ?
Highly doubt it. It would go against the unified systems architecture goal if CPU and iGPU have independent memory.
Quote:
Originally Posted by Jared2608 View Post

Even if they used it like sideport memory, that would surely exclude anyone with a current FM2 board. Which would be kind of sad.
GDDR5 and DDR3 are mutually exclusive as stated in the article. If you choose GDDR5 as system memory, you don't get DDR3, and vice versa.
 

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FM2 is supposed to have quiet a long run. I highly doubt Kevari will come out for a different socket. If it does, it would probably be something like "FM2+" and it would be backwards compatible. FM2's only been out since October 2012. It would be very unlike AMD to get rid of FM2 that quickly.
 
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