AMD - Piledriver chitchat

[scaryjim]

Interesting to note that they compared it to Kaveri and Carrizo running below their peak memory bandwidth - I believe even the mobile versions support at lest DDR3-1866, even if they don't get that very often in OEM laptops...?

[watercooled]

Off topic a bit but it seems like we were spot on about NVlink predictions - it's a HPC GPU-GPU interconnect, and funnily enough Intel didn't integrate it into their CPUs!

http://anandtech.com/show/10229/nvid...es-dgx1-server

[DanceswithUnix]

I see the Excavator based Athlon X4 845 is popping up in the shops around the £50 mark

http://www.ebuyer.com/745517-amd-ath...-ad845xackasbx

There seems to be SKUs for the 860K, 870K, 880K and 7860K with the new cooler as well.

[scaryjim]

Off topic a bit but it seems like we were spot on about NVlink predictions - it's a HPC GPU-GPU interconnect, and funnily enough Intel didn't integrate it into their CPUs!

http://anandtech.com/show/10229/nvid...es-dgx1-server

Having read up a bit more (you can probably guess why ) it goes beyond that - it's a method of unified memory access, but as far as I can tell it's ONLY for direct memory access between processors; so even where the CPU supports NVLink it will also need a PCIe connection between the GPU and CPU. There's a slide somewhere showing the details: I'll see if I can dig it up again and post a link.

It's good to see the 845 appearing at retail, but tbh I'm not sure where the market for it is. I suppose if you *must* build a budget PC right now and you're going with a ~ £100 GPU it might be an option, but I'd think most people will wait until AM4 launches... Nice to see options for the new quiet cooler though. The 7860k with the new cooler for £93 is a pretty good deal...

[watercooled]

Yeah I was also persuaded to do a bit of reading. It does seem, as others have said, quite similar in principal to Hypertransport/QPI. I guess it was born out of necessity (I mean they could have adopted an existing standard, but why would Nvidia take that option? ) given their ambitions to scale up in the datacentre, but it's really not something new and miraculous like it's being made out to be in the media.

The 845 is definitely interesting from a performance standpoint but it only makes me wonder why they haven't released at least a couple of APUs? Maybe they're so close to AM4 release they don't want to risk cannibalising sales or building up yet another inventory they can't shift?

But yeah, lower-end CPUs without any IGP (even a really cut back one) are making less and less sense - by the time you pair it with a GPU it would in many cases be cheaper to just get an equivalent APU. The budget range where it makes sense seems pretty slim!

[scaryjim]

... by the time you pair it with a GPU it would in many cases be cheaper to just get an equivalent APU. ...

Well, depends on what you're looking for in performance terms. Ebuyer has the A10 7860k listed at around £93, and that'll give you the equivalent performance of a £50 - £60 GPU, so if that's all you were after performance-wise the APU makes sense. OTOH, once you're using a dGPU there's no point paying extra for the IGP, and the X4 845 is around £15 cheaper than the cheapest A8 APU, plus it has a > 10% clock speed advantage (quite apart from being a newer revision of the architecture). There's plenty of < £100 GPUs out there that will destroy the A10's graphics for gaming, at which point a quad core CPU at £50 starts looking like a much better deal...

EDIT:

Not that I've not got much on at the minute, but I just had a play on ebuyer. I can throw together a gaming build with the X4 845, an R7 360 OC, 4GB DDR3-1600 and a 1TB HDD, plus case, a Freesync 1080p monitor, and a mouse/keyboard/headset, for almost spot on £400. If you went for a non freesync monitor then a 750 Ti's an option, or another £10 - £20 brings the R7 370 and GTX 950 into play too. Chuck a Windows license on and you're still the right side of £500 for a complete gaming rig including monitor and headset (OK, the headset won't be up to much, but if you're trying to get a complete gaming rig for £500 you'll probably accept that ). With DX12 and Vulkan in the offing, I reckon a £50 AMD quad is easily as good an option as a £50 Intel dual core....

[spacein_vader]

I'm planning to get a X4 875 as from what I've seen so far it should be the best circa £50 processor for transcoding & the server will be running headless. Sure that's a niche use but still.

[watercooled]

@Scaryjim: All very true, I just mean it seems strange to release a part with the GPU disabled, but no desktop parts with the fully enabled newer GPU and CPU vs Kaveri. Unless like I say they're so close to AM4 they don't want to throw a spanner in the works.

[scaryjim]

... it seems strange to release a part with the GPU disabled, but no desktop parts with the fully enabled newer GPU and CPU vs Kaveri. Unless like I say they're so close to AM4 they don't want to throw a spanner in the works.

My guess would be that most of the Carrizo silicon is going to mobile, and potentially the way the chips are yielding means there's not really enough silicon for multiple updated desktop product lines. If the majority of defects are in the IGP but there's also one or two chips that don't make the voltage/clock speed standards for mobile silicon, it's probably more economic to harvest all the low-binned dies into Athlons rather than try to put out both Athlons and A-series APUs, particularly if they're still producing desktop Kaveri silicon (which the A10 7860k would suggest they are).

That said, I'd be amazed if the future planning for AM4 didn't have something to do with it. Kind of bored of waiting for that now - it feels like we've been discussing AMD needing a new platform for four or five years...!

[CAT-THE-FIFTH]

From what I heard it is more down to FM2+ not supporting the enhanced power regulation on the Carrizo GPU.

[watercooled]

Yeah, in all fairness AM3/+ was looking dated by the time Bulldozer came out.

IIRC Bulldozer even had an on-die PCIe controller which never ended up getting used because they stuck with the old platform. It didn't help matters in terms of power consumption either - they were already behind before you even considered the CPU.

I know they valued keeping socket compatibility but it wasn't fully compatible with AM3 (non-plus) I do wonder why they chose not to just bring out another socket; they did it for FM1 after all! Maybe budget was the reason?

[scaryjim]

... I do wonder why they chose not to just bring out another socket; they did it for FM1 after all! Maybe budget was the reason?

I think part of it was wanting to maintain consistency in the 1P server market as possible - they'd already decided to serve that market with AM3 and at the time of BUlldozer's release DDR4 wasn't ready, so they had to stick with a DDR3 platform and they already had one that was well understood in the server market. Interestingly, FX was released 5 years ago this October, and 5 years is a fairly typical enterprise hardware refresh cycle...

I think the other part of it might be that they were expecting faster mainstream DDR4 adoption. Modules were announced as far back as 2012, and hit consumer (well, enthusiast) products in mid 2014 with Intel's X99 platform, but in the 18 months since we've not really seen a big move towards consumer DDR4; it's only really started to trickle through in the last few month, and even then it's been in higher-end enthusiast builds. I strongly believe they were holding off from putting out a unified APU/CPU platform until they thought the mainstream market was ready for DDR4 so they wouldn't have to do the whole hybrid DDR3/DDR4 thing, and that that took longer than they were expecting.

Of course, for FM1 they *needed* a new socket/platform because they had to route video signals from the IGP, although it was rather un-AMD-like to cycle through FM1 and FM2 so quickly without any level of compatibility. Not sure if that was deliberate, or if they just messed up the planning with FM1 and simply weren't able to reuse when they came to spec the socket for Piledriver-based APUs (after all, they needed a new socket for FX CPUs, but at least there they kept backwards compatibility to existing AM3 CPUs...). The basic platform remained the same in the transition between FMX sockets, after all, much like the AM2(+)/3(+) platforms.

[CAT-THE-FIFTH]

A comparison of the current of FM2+ CPUs including the Athlon II X4 845:

http://wccftech.com/amd-athlon-a10-roundup/

[scaryjim]

Interesting piece CAT, thanks for sharing The X4 845 really does look like a good chip, doesn't it. And interesting to see that a GTX950 @ 1080p is the limiting factor in most games: would've been interesting to see a Pentium in there for comparison to the 845, since you can't get an i3 at that price...

if only FM2+ wasn't essentially a dead platform *sigh*. OTOH Bristol Ridge might be a good stopgap while waiting for Zen CPUs to launch....

[DanceswithUnix]

if only FM2+ wasn't essentially a dead platform *sigh*. OTOH Bristol Ridge might be a good stopgap while waiting for Zen CPUs to launch....

I presume I am not the only one holding off any purchase until AM4 comes out. And yes, for my Bristol Ridge would no doubt be fine.

[scaryjim]

I think it would be worse for AMD if Polaris and Pascal weren't both due this summer as well. There are actually a lot of reasons to delay buying a new computer right now. The problem will come if there is any delay between Polaris and AM4 as a platform ... there's only so long people will hold off, and when they can get Skylake + Polaris now they're not necessarily going to wait for Bristol Ridge + Polaris, even with the promise of a Zen upgrade down the line...

So many chances for the whole thing to go tits up...