crashnburn wrote:
SaskFellow wrote:There are 2K displays on TaoBao... I wonder if the FHD kit can handle a 2K screen. Still the display would be expensive, and the graphics hardware would cry.
It's too bad we can't mount 3xxx series chips in these machines. Though on TaoBao seems someone has an i7-3860QM in a T420. It's not the CPU cores that are so much more powerful,
it's the iGPU that is so much better, lower power memory, and lower power cores, if the chipset would play nice with a 38*0QM, I'd just simply disable hyper threading and I'd risk bricking the mobo in my T420s. As it is an i7-28*0QM just isn't enough of an upgrade over the i7-2640M in the system to risk it.
So, essentially the GPU is not good enough for 2K? PS: Assuming that we want GPU to take the load and not CPU
I thought most of these next gen were capable of driving 4K.
http://forum.thinkpads.com/viewtopic.php?f=18&t=120427
Would a next gen be more able.. say T430 + .. series?
I had a fancy post up talking about the differences, and then I accidentally closed the window...
Anyway...
IvyBridge HD4000 compared to Sandybridge HD3000: HD4000 is at least 50% faster and supports 3 displays rather than 2. A review I read which used a system that could take either or, pitted an i7-2960XM vs an i7-2860QM, the cores are only about 5% faster clock for clock, but the HD4000 really beats up on the HD3000. Also Ivy uses less power, has a few extra extensions/instruction sets, and allows lower voltage DDR3L, which also helps to lower cpu temps, as it drops the memory controllers voltage.
The link, doesn't talk about dedicated GPUs making any difference in the ability for the 4K screen, to be drawn too at a higher refresh rate. So it's probably a hardware limitation. Takes more ram as well to draw to a 4K screen and faster too, as well as the bandwidth limits.
Like the display connections to the screens on the T420/T420s machines, I'm pretty sure the T420s uses eDP rather than LVDS.
LVDS standards:
Single Chan: 1400x1050 @60hz
Dual Chan: 2048x1536 @60hz has 7.56Gbit of bandwidth
Dual channel: 1920x1200 18bit @60hz with 16 signal wires
Dual channel: 1920x1200 24bit @60hz with 20 signal wires
Quad channel: 1920x1200 24bit @120hz with 40 signal wires
eDP or embedded Display Link:
eDPv1.1(2009): Production, changes and tweaks from Prototype only eDPv1.0. Production in 2010.
eDPv1.2(2010): Adds Panel control through Aux Channel. Production in 2011.
eDPv1.3(2011): Adds PSR aka Panel Self Refresh and clarity on how to use the 5.4Gbit transfer mode. Production in 2012.
1-2 Pairs(2 signal wires per pair): 1.6 to 5.4Gbit per pair
1 pair = 1600x900 18bit @60hz
2 pairs = 1920x1200 24bit @60hz
4 pairs = 1920x1200 24bit @120hz
I believe the T420/T430 models only use a single pair equipped eDP connection, which is why the FHD kit has problems. The T420s and T430s uses a dual pair eDP connection, so the FHD kit is almost straight forward. Both would explain why a 2K upgrade kit would have to disable external display connections or cause problems for them, because you are borrowing connection pairs from somewhere to drive the screen.
As a bonus, the eDP standard that came out during the production of the T420 series, but probably wasn't put into use until the T440 series:
eDPv1.4(2012): Partial frame update capability to PSR, additional link modes, lower voltage, transport data compression, regional backlight control, multi-touch input is sent through the aux line to the system processor, and the electrical characteristics of the connection have been improved to support a wider array of uses. Production in 2014. It also has seen several revisions including one that allows 8.1Gbits per connection pair and 8K displays.
Edit of note:
If our machines support eDP v1.3, the PSR frame buffer can be used to improve LCD performance if one is using the LCD Overdrive feature. Of course that means the display itself would have to be eDP v1.3 compatible as the display houses the additional hardware for PSR mode. Interesting indeed!
