51–60 of 74 posts
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>> The only real advantage for a new spec is to bump the density. And DDR4 can apparently support 128GB per module. Those apparently exist, but you can't find even a 32GB at Newegg.
Above 8 gigs per module you're going to need buffered ram. Check in the ECC section.
How much difference is there between GDDR and regular DDR? I think that GDDR runs at higher voltages and temps than regular DDR. I'm assuming if GDDR5 is available, then it's kind of inevitable that regular DDR 5 would be coming at some point.
I thought the main difference with graphical RAM was that the monitor output DAC could read from memory at all times, regardless of what the GPU is doing with it. And GDDR n is not the same generation as DDR n ; the last GDDRs (4,5) have been based off DDR3, I think.
Are there applications which will see significant benefit from a new generation of DRAM, or higher speeds? Games, for instance, seem to see only very small performance differences from changing RAM speeds.
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Latency is limited by the speed of electricity which is a large fraction of the speed of light, so unless you move DDR closer to the CPU it physically can't get 2x as fast... ever. light speed * 0.951 (electricity) / 2 (round trip) / 2 feet (CPU to furthest RAM chip along a wire) ~= 250 million cycles per second. However, cache is now huge. So, it's latency is usually less of an issue than sequential reads/writes and…
I keep hearing this, but it doesn't jibe with the RAM timings I see. tRAS is usually 50ns or so, and propagation delay is 2ns or so (see below). What gives? My suspicion is that amplifying the differential voltages produced by femtocoulombs of charge at 100% reliability is a harder problem than moving the DRAM chips closer to the CPU, and that speed-of-light has gotten the blame in "pop architecture" due to sloppy ov…
On the other hand sequential access bandwith is limited almost entirely by the external interface and has more to with economical factors (pin count is major part of IC price) than any physical limitations.
Would the equivalent amount of DDR5 actually feel any different to DDR4 to the end user? It seems like hardware is getting better but basic software (web browser etc) is getting more complicated/bloated at the same rate, so things don't actually feel 10x faster than they did a few years ago.
Do you have an SSD yet? A good one? Computers with good SSDs and not too much bloatware (relevant on Windows) do feel faster to me than computers used to be. I think people can get nostalgic accidentally and overestimate how fast things were in the past. I remember multi-minute loads for games on my Commodore 64. I remember multi-minute Windows 3.1 bootups. I remember watching a JPEG progressively creep in on the ear…
No one's asked me yet why these smaller SSD thingys are so much more expensive than larger hard drives, but I prepared the answer a long time ago:
They make your computer feel 10x faster.
Only cheapskates and the stubborn would pass on an SSD.
So, it's been a while since I tinkered with hardware, but I'm making the blind assumption that although the bus speed is twice as fast as DDR4, there is also twice the read latency, as has always been the case with DDR memory, meaning the net read latency improvement is basically nil. Of course we expect every generation of Double Data Rate memory to double the data rate. But it's always been a bit misleading to say…
Latency is limited by the speed of electricity which is a large fraction of the speed of light, so unless you move DDR closer to the CPU it physically can't get 2x as fast... ever. light speed * 0.951 (electricity) / 2 (round trip) / 2 feet (CPU to furthest RAM chip along a wire) ~= 250 million cycles per second. However, cache is now huge. So, it's latency is usually less of an issue than sequential reads/writes and…
You're point isn't invalid but it's sort of misapplied. In fact the latency of DRAM on modern systems is dominated almost entirely by precharge time within the memory IC, which is about an order of magnitude slower than signal propagation. And it's not changing, either. DRAM cycles have been sitting at around 60 MHz for a decade and a half. We're dropping voltage as we shrink the cells, and so there's no net increase. Realistically signal propagation will never be the limit.
JEDEC officially specs DDR4 RAM up to 2133 MHz. But manufacturers seem to have left this far behind already, with Corsair and G.Skill shipping modules at 4200 MHz. I don't see why JEDEC doesn't just add a few more rows to the table of official speeds. The only real advantage for a new spec is to bump the density.
I bought last year DDR3 RAM, 2400mhz.
So, when DDR4 started to be sold, capped at 2133, DD3 2400 was already sort of easy to find (and it is faster than the DDR4 too, due to smaller latency, the few times I decided to run my computer in some OC competition that relied on RAM it ended on the top 1% of the air cooled machines despite not being an exceptional machine neither prepared to OC, Intel XMP runs crazy fast on my machine, the OC people I talked all said it was because of my fast DDR3 RAM).
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Do you have an SSD yet? A good one? Computers with good SSDs and not too much bloatware (relevant on Windows) do feel faster to me than computers used to be. I think people can get nostalgic accidentally and overestimate how fast things were in the past. I remember multi-minute loads for games on my Commodore 64. I remember multi-minute Windows 3.1 bootups. I remember watching a JPEG progressively creep in on the ear…
Agreed. Load times were bad in the past. No one's asked me yet why these smaller SSD thingys are so much more expensive than larger hard drives, but I prepared the answer a long time ago: They make your computer feel 10x faster. Only cheapskates and the stubborn would pass on an SSD.
Even a year ago I was still going "eeehhhhhh, weeelllll, maaayybee..." but sometime in the last year I'd say we crossed over for any professional. It's no longer a matter of paying $100 for a big-enough spinning rust or $600 for a too-small SSD, now it's more like "Do I want a really fast 512GB or a slow 4TB for the same price?", which are both as of right now ~$150 give or take $30 depending on your quality needs. (I just checked.) That's still quite the spread on size, but you can fit a lot in 512GB.
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If cas latency haven't changed for 20 years, and the memory wall in general being a huge pain, does anybody know why didn't some sort of 2.5D memory(even using low-resolution lithography and carriers cheaper than silicon), haven't entered the market ?
Heat, RAM puts out a lot more than you might think. That said, for low power devices like cellphones you can use different packaging and cut latency. Also, AMD for example uses stacked ram (HBM), but that needs very special packaging and active cooling. http://www.amd.com/en-us/innovations/software-technologies/h... https://en.wikipedia.org/wiki/High_Bandwidth_Memory