What does 64 bit do?

[turner112 52]

I actually don't really know the benefits - I know it's good, but just curious what effect this will have on my relatively "old" machine.

XP11 runs fairly well. Looking forward to P3D v4...

[Lars Moellebjerg 13]

To keep it very simple: A 32 bit program can only use around 3GB of your memory. If you have more, it won't use it (but of course other programs running on the computer can use the extra memory).

Run Prepar3D v3 on a system with 4GB, and it see 3GB it can use. Run it on a system with 64GB, and it still only see 3GB it can use. If you want to add too many ATC aircrafts, too detailed models, too much scenery, ... it will fill the 3GB, not be able to see more and run out of memory.

It used to not be a big deal - before you had enough data to fill 3GB your CPU/GPU would already be overused and the simulator unplayable. But as hardware has progressed this is no longer the case.

A 64bit process like Prepar3D v4 can use all memory on your system, so you can simply install more memory and keep adding content until your CPU/GPU again becomes unable to handle it.

[Chock 17,769]

First up you need to be aware that 64 Bit can refer to hardware as well as software, i.e. you can have a 64 Bit program, or a 64 Bit piece of hardware such as a CPU.

A Bit is a Binary Digit, and it can hold one of two values, either a 1 or a 0. In computer terms, that one and 1 and 0 can be used to represent all kinds of stuff, typically either a yes or a no in the program which is running i.e. it could be something like your computer asking: 'Has your flight sim plane crashed into the ground? if yes, then allocate a 1 value, if no then allocate a 0 value'. Then your program will see the allocated value and whatever that value is (either 1 or 0) will trigger it to do the next bit of processing, i.e if it sees a 1 (i.e. yes, your plane has crashed into the ground), that might trigger the sim to play an explosion animation or whatever. This is essentially how all programs work and it therefore stands to reason the more of this stuff it can process and assign and the faster it can do it, the more efficiently a program or a computer will run.

As the larger number suggests, a 64 Bit CPU (i.e the hardware) can calculate stuff twice as fast as a 32-bit one can, but more importantly where flight sims and stuff are concerned, the 64 Bit process itself, can allocate significantly more random access memory (RAM) to a process than the 32 Bit process ever could, so in addition to doing stuff quicker, 64 Bit can handle more stuff at that quicker speed too.

Where flight sims are concerned, that is important because...

There is a 4-gigabyte limit imposed by the 32-bit process (that's a hard limit, caused by the mathematical value of 32, whereby how much memory which can be used is a multiple of the number, and there is very little which can be done to change that, although when I say very little, there actually is something which can change it. But only tiny bit. See below*).

In fact this limitation can actually be worse than the above sounds, in that some software will not use even 4Gb of memory since it will be designed to keep some free for the operating system. You may recall a few years ago that many people were applying the '3Gb switch' tweak to flight simulators to allow it to use a bit more memory; that's what all that stuff was about and is why for example the Steam version of FSX runs a bit better than the older boxed version, because it had all the tweaks like that and for high memory fixes applied to it by default instead of requiring one to apply service packs and config file tweaks etc.

The 64 Bit difference is hugely significant in that it can support allocating and using up to 1,024 GB of both physical and addressable memory, so unlike with the calculations, which as noted are done twice as fast, the ability to use your PC's hardware is literally 256 times more capable than 32 Bit. This is why everyone is running around like a dog with two tails over all this 64 bit malarkey, because that means your computer will not have programs such as flight simulators crashing due to not being able to utilise the physical capabilities of your computer. Your computer may slow down of course, or drop frame rates, since it still has the same clock and bus speeds, but theoretically it should not crash the program owing to it locking up when it can't use any more memory.

*More recent 64 bit operating systems can address up to 16 terabytes of virtual memory, dividing it equally between the operating system and anything else which is running on the computer. Now as noted, a 32 Bit program can only use up to 4Gb of memory, but, since a 64 Bit operating system can assign craploads of virtual memory, that does mean that with a 64 Bit operating system, your computer can actually allocate that full 4Gb of oomph to a program such as Flight Simulator, so whilst it is true that 32 Bit is limited to 4Gb, it can at least go all the way up to that limit with the assistance of a modern 64 Bit OS.

 

[Mr_LoL 10]

Quick question

When I'm playing Cities Skylines which is a 64 bit game, VAS usage gets to 12GB. Where is that VAS usage being stored as that game only uses 4GB of physical memory. I just want to know if I should get an extra 16GB of Ram for P3D.

 

Thanks

[MarkDH 234]

1 hour ago, Chock said:

As the larger number suggests, a 64 Bit CPU (i.e the hardware) can calculate stuff twice as fast as a 32-bit one can

Well, no. It means it can move data around in chunks that are twice as big. I'm not sure how you're equating that to calculation speed, which would primarily be a function of the clock speeds of various subsystems.

[MarkDH 234]

44 minutes ago, Mr_LoL said:

I just want to know if I should get an extra 16GB of Ram for P3D.

YES. Windows uses virtual memory, which means it can fool your programs into thinking it has more memory than it actually has by swapping bits of data in and out of memory to a disk file behind the scenes (historically this is called 'paging'). This is a very reliable and mature technology but however well-optimised the paging algorithms are it's super-slow compared to proper memory. Paging to SSDs is much faster than to mechanical disk drives, but it still doesn't compare to RAM speeds.

So you really want to have as much physical memory as you are likely to use. And because your game (or P3D ) is not the only thing running, this means as much memory as all the programs running at the same time are likely to use. And probably a bit more for slack. With a 64-bit address space, the new limit will be your OS's or your motherboard's ability to host actual RAM. I recently discovered Windows 7 Home Premium (my current OS) is limited to 16Gb, which is a ###### because I installed 32Gb specifically for X-Plane. My new motherboard can host a maximum of 64Gb.

[Chock 17,769]

14 minutes ago, MarkDH said:

Well, no. It means it can move data around in chunks that are twice as big. I'm not sure how you're equating that to calculation speed, which would primarily be a function of the clock speeds of various subsystems.

Simple, if a 64 bit processor can do twice the tasks of a 32 bit one (which it can), it stands to reason that it is twice as fast, in the same way that one person washing and one person drying is obviously faster than one person doing the washing and then starting on the drying after that.

[MarkDH 234]

4 minutes ago, Chock said:

Simple, if a 64 bit processor can do twice the tasks of a 32 bit one (which it can)

There you go again. Same answer.

[vgbaron 3,620]

@Chock - you're comparing apples and oranges. Quantity and speed.

 

*IF* a 64bit system could do DOUBLE the tasks IN THE SAME TIME - then yes, it's twice as fast but in practice it's just not that black and white. Is 64bit faster than 32bit? Nope - clock speed is clock speed. Is the throughput of the activity faster? Yes but not double - that would depend on other factors. In practice it could also be slower under certain circumstances.

It's just not 2+2=4.

Vic

[neumanix 113]

Listen up now mr. Chock. You're on about that 64bits is somehow twice as fast as 32bits, which is absolute nonsense and isn't in any way even relevant.

First, 33 bits can hold twice the amount of data than 32bits. The formula is very simple, it's the base to some power.

In the case of binary, the base is 2, so the amount of data 32bits can hold is 2 to the power of 32 which is roughly 4 billion (4 Gb).

A 64 bit processor, which most of us use today, does NOT do twice the tasks as a 32bit one does.

It can address an astronomically larger amount of data, but it has the exact same instructions as a 32bit CPU have and run at similar clock speeds.

And finally, 64bits doesn't solve the OOM problem. It just gives a new solution, which requires digging into your wallet and buying more RAM :)

 

[charlie130 196]

11 minutes ago, neumanix said:

And finally, 64bits doesn't solve the OOM problem. It just gives a new solution, which requires digging into your wallet and buying more RAM :)

 

Also as devs produce 64 bit software and not just 32 bit software patched to run, in 64 bits. Then especially in 64 bit graphics, a 4Gb 980 won't be enough Vram. We are going to need a Titan or something like it with 12 GB+++. 

More=more!

Better start saving for hardware upgrades!

Regards

David

 

[neumanix 113]

Just to set things straight, there are no 64bit graphic modes yet :) When we talk about graphics and the 32bit mode we run, it means we use 24 bits for color data and 8 bits as an alpha (transparency) channel. Altogether it's 8bits for RED, 8bits for BLUE, 8bits for GREEN and 8bits for transparency, a total of 32 bits.

The requirement for up to 12GB and beyond, is only if you increase the LOD and autogen drawing distance to values above what the UI provides, i.e. tweaking the cfg file.

 

[swiesma 625]

64Bit twice as fast as 32 Bit? Maaaaaan I need a 200 MBit thingy!!!!!! Wait..... what?!

[WarpD 824]

3 hours ago, Chock said:

Simple, if a 64 bit processor can do twice the tasks of a 32 bit one (which it can), it stands to reason that it is twice as fast, in the same way that one person washing and one person drying is obviously faster than one person doing the washing and then starting on the drying after that.

64-bit doesn't do twice the anything... seriously.  It's just not how all of this works.  64-bit changes the size of the registers built inside the CPU.  Changing them from 32-bit to 64-bit doesn't double memory, doesn't double computing speed, and you can't do twice the instructions as before.  It only raises memory access capability exponentially (powers of 2) and allows for twice the size of a numeric value.

That's it.

[gregmorin 199]

Thanks Ed

Greg