Overclock.net › Forums › Graphics Cards › Graphics Cards - General › A few questions about Vram and SLI/Xfire
New Posts  All Forums:Forum Nav:

A few questions about Vram and SLI/Xfire

post #1 of 8
Thread Starter 
1.Why doesnt the memory compund between the two cards, even though the processors do?
2.If a dual GPU setup doesnt have compund Vram how come single PCB dual GPU cards are marketed as 4gb if it can only use the Vram of one GPU?
3.If the vram of one GFX card is only used would you be able to set one cards memory to really low to increase its core clock?
4.Does the memory bit width (256 bit, 320 bit) compund even if the memory doesnt?
Oppress This!
(13 items)
 
  
CPUMotherboardGraphicsRAM
Phenom 2 X4 B55BE @ 3.7 ASUS M4A89GTD-PRO USB3 GTX 470 + GTX 275 SOC 4gb Crucial Ballistix T 1600 6-8-6-20-24 1T 
Hard DriveOptical DriveOSMonitor
2xWD640AAHLS + Hitachi 2TB 7200RPM + 2x150gb VRapt HP IDE + LG SATA Win 7 x64 ult 15" 1024x768 Dell (visually impaired) 
PowerCase
XFX XXX 650w (green fan) Antec 300 (Heavily Modded) 
  hide details  
Reply
Oppress This!
(13 items)
 
  
CPUMotherboardGraphicsRAM
Phenom 2 X4 B55BE @ 3.7 ASUS M4A89GTD-PRO USB3 GTX 470 + GTX 275 SOC 4gb Crucial Ballistix T 1600 6-8-6-20-24 1T 
Hard DriveOptical DriveOSMonitor
2xWD640AAHLS + Hitachi 2TB 7200RPM + 2x150gb VRapt HP IDE + LG SATA Win 7 x64 ult 15" 1024x768 Dell (visually impaired) 
PowerCase
XFX XXX 650w (green fan) Antec 300 (Heavily Modded) 
  hide details  
Reply
post #2 of 8
Because Crossfire does not compound the VRam while SLI does.
In SLI the memory is as low as the lowest memory card.
post #3 of 8
1. dunno for sure but maybe something to do with ram latency over Sli bridge.
2.Because it will have 4gb,its just 2gb mirrored,but it dont state 4gb of usable...does it now wink.gif
3. dunno
4. dunno

EDIT:
Quote:
Originally Posted by Paratrooper1n0;13659994 
Crossfire does not compound the VRam while SLI does

Does it?
Edited by superj1977 - 5/27/11 at 4:12pm
Le Box of Black
(19 items)
 
  
CPUMotherboardGraphicsRAM
i7 930 Gigabyte X58A-UD7 r2.0 GTX 770 16GB Corsair Vengeance in Triple channel mode ;) 
Hard DriveHard DriveHard DriveHard Drive
Ocz Vertex 2  Samsung F1  Samsung F3 Samsung F1 
Optical DriveOSMonitorKeyboard
Sammie Dvd rw Windows 7 64Bit HZ281HPB 1200p / HP IPS 1080p / Samsung Syncmas... Qpad MK80 (Blue switch), SteelSeries 7G (Cherry... 
PowerCaseMouseMouse Pad
HX1000 CM-Stacker 832 Flipped Naos 3200,G5,G400,G400s, G300, Kone+ Razor Destructor and Steelseries Qck 
AudioAudioAudio
X-Fi Fatal1ty  ATH-T500 / AH-D510 Samson CO1U PAK Condenser Mic  
  hide details  
Reply
Le Box of Black
(19 items)
 
  
CPUMotherboardGraphicsRAM
i7 930 Gigabyte X58A-UD7 r2.0 GTX 770 16GB Corsair Vengeance in Triple channel mode ;) 
Hard DriveHard DriveHard DriveHard Drive
Ocz Vertex 2  Samsung F1  Samsung F3 Samsung F1 
Optical DriveOSMonitorKeyboard
Sammie Dvd rw Windows 7 64Bit HZ281HPB 1200p / HP IPS 1080p / Samsung Syncmas... Qpad MK80 (Blue switch), SteelSeries 7G (Cherry... 
PowerCaseMouseMouse Pad
HX1000 CM-Stacker 832 Flipped Naos 3200,G5,G400,G400s, G300, Kone+ Razor Destructor and Steelseries Qck 
AudioAudioAudio
X-Fi Fatal1ty  ATH-T500 / AH-D510 Samson CO1U PAK Condenser Mic  
  hide details  
Reply
post #4 of 8
When you run 2 cards in sli or crossfire the work is split up between both cards. Each card still only has its rated memory to work with though.
post #5 of 8
I don't know exactly what 'Compund' means but it's probably something between 'coorporate', 'add up' and 'compute'. New word, keeping that one.

1. Crossfire or SLI would get a negative performance hit if one cards started to read and write to the memory of the other card through an oh so tiny bus. So each card stores it's own memory. Both memories contain pretty much thesame.

2. Answered in 1.

3. If you do that, one card would operate really slow, again, each card _needs_ its own memory fully. Sharing it or removing/crippling it is out of the question.

4. Yeah, in a way you can say its i.e. 2x256 bit = 512 bit (in speed-terms, not in actual bandwidth, note!) memory. It's the same data being read from two seperate banks. Data throughput is double. Speed probably isn't.
post #6 of 8
Thread Starter 
Quote:
Originally Posted by strandtentje;13660027 
I don't know exactly what 'Compund' means but it's probably something between 'coorporate', 'add up' and 'compute'. New word, keeping that one.

1. Crossfire or SLI would get a negative performance hit if one cards started to read and write to the memory of the other card through an oh so tiny bus. So each card stores it's own memory. Both memories contain pretty much thesame.

2. Answered in 1.

3. If you do that, one card would operate really slow, again, each card _needs_ its own memory fully. Sharing it or removing/crippling it is out of the question.

4. Yeah, in a way you can say its i.e. 2x256 bit = 512 bit (in speed-terms, not in actual bandwidth, note!) memory. It's the same data being read from two seperate banks. Data throughput is double. Speed probably isn't.

Compound means to collaborate, or add together to forma comon goal.
Oppress This!
(13 items)
 
  
CPUMotherboardGraphicsRAM
Phenom 2 X4 B55BE @ 3.7 ASUS M4A89GTD-PRO USB3 GTX 470 + GTX 275 SOC 4gb Crucial Ballistix T 1600 6-8-6-20-24 1T 
Hard DriveOptical DriveOSMonitor
2xWD640AAHLS + Hitachi 2TB 7200RPM + 2x150gb VRapt HP IDE + LG SATA Win 7 x64 ult 15" 1024x768 Dell (visually impaired) 
PowerCase
XFX XXX 650w (green fan) Antec 300 (Heavily Modded) 
  hide details  
Reply
Oppress This!
(13 items)
 
  
CPUMotherboardGraphicsRAM
Phenom 2 X4 B55BE @ 3.7 ASUS M4A89GTD-PRO USB3 GTX 470 + GTX 275 SOC 4gb Crucial Ballistix T 1600 6-8-6-20-24 1T 
Hard DriveOptical DriveOSMonitor
2xWD640AAHLS + Hitachi 2TB 7200RPM + 2x150gb VRapt HP IDE + LG SATA Win 7 x64 ult 15" 1024x768 Dell (visually impaired) 
PowerCase
XFX XXX 650w (green fan) Antec 300 (Heavily Modded) 
  hide details  
Reply
post #7 of 8
VRAM does compound as the two GPUs do. VRAM is associated with a particular GPU. When 2 GPUs are put together to work, each GPU works with its own VRAM.

My crude analogy: A man (CPU) has 2 arms (VRAM). When 2 men are put together to do a task, there are 4 arms in total but it is still 2 arms per man. The task will be done faster, of course.

Always thinks 'VRAM per GPU'. When a 'single PCB with dual GPU' card like GTX590 or HD6990 is marketed, the total VRAM of the card is highlighted (instead of VRAM per GPU) as a marketing gimmick. It is certainly not a lie as the entire amount of VRAM will be utilized by both GPUs and so nothing sits idling or wasted.
Edited by windfire - 5/27/11 at 4:58pm
post #8 of 8
Quote:
Originally Posted by Smoblikat;13659948 
1.Why doesnt the memory compund between the two cards, even though the processors do?
2.If a dual GPU setup doesnt have compund Vram how come single PCB dual GPU cards are marketed as 4gb if it can only use the Vram of one GPU?
3.If the vram of one GFX card is only used would you be able to set one cards memory to really low to increase its core clock?
4.Does the memory bit width (256 bit, 320 bit) compund even if the memory doesnt?

1. Each processor needs its own framebuffer (read: memory).
2. Because the science of marketing and the art of hype dictate so.
3. If you want to make things run horribly, sure.
4. No, each GPU has its own memory bit width.
Avalon
(18 items)
 
   
CPUMotherboardGraphicsRAM
Intel Core i5 6600k MSI H170A Gaming Pro GIGABYTE GTX1080  Kingston HyperX FURY Black 64GB DDR4 
Hard DriveHard DriveHard DriveOptical Drive
Samsung SSD 850 EVO 500GB Western Digital Caviar Green 2TB Samsung SSD 840 EVO 120GB LG DVD/RW 
CoolingOSOSMonitor
CoolerMaster 212 Microsoft Windows 10 Pro Apple OS X El Capitan Acer AT3265 32" 1080p 60Hz 
MonitorKeyboardPowerCase
Samsung SyncMaster 192n 20" 1280x1024 75Hz AZIO Mechanical Corsair CX750 CoolerMaster CMII Advanced 
MouseAudio
E-Blue Mazer Realtek High Definition 
CPUMotherboardGraphicsRAM
Intel Core i7 3630QM MSI CZ-17 NVIDIA GeForce GTX 675MX Patriot Memory PSD38G1600L2S 
RAMHard DriveHard DriveOptical Drive
G.Skill F3-1600C10-8GSQ Samsung SSD 840 EVO Samsung ST-2000 TSST DVD/BD SN-406AB 
OSMonitor
Microsoft Windows 10 Pro 64-bit 17" 1920×1080 60Hz 
  hide details  
Reply
Avalon
(18 items)
 
   
CPUMotherboardGraphicsRAM
Intel Core i5 6600k MSI H170A Gaming Pro GIGABYTE GTX1080  Kingston HyperX FURY Black 64GB DDR4 
Hard DriveHard DriveHard DriveOptical Drive
Samsung SSD 850 EVO 500GB Western Digital Caviar Green 2TB Samsung SSD 840 EVO 120GB LG DVD/RW 
CoolingOSOSMonitor
CoolerMaster 212 Microsoft Windows 10 Pro Apple OS X El Capitan Acer AT3265 32" 1080p 60Hz 
MonitorKeyboardPowerCase
Samsung SyncMaster 192n 20" 1280x1024 75Hz AZIO Mechanical Corsair CX750 CoolerMaster CMII Advanced 
MouseAudio
E-Blue Mazer Realtek High Definition 
CPUMotherboardGraphicsRAM
Intel Core i7 3630QM MSI CZ-17 NVIDIA GeForce GTX 675MX Patriot Memory PSD38G1600L2S 
RAMHard DriveHard DriveOptical Drive
G.Skill F3-1600C10-8GSQ Samsung SSD 840 EVO Samsung ST-2000 TSST DVD/BD SN-406AB 
OSMonitor
Microsoft Windows 10 Pro 64-bit 17" 1920×1080 60Hz 
  hide details  
Reply
New Posts  All Forums:Forum Nav:
  Return Home
  Back to Forum: Graphics Cards - General
Overclock.net › Forums › Graphics Cards › Graphics Cards - General › A few questions about Vram and SLI/Xfire