GPU drivers on XP only support HBR1. You need to find a custom resolution and refresh rate that you are happy with within the limit. If you want 144hz then lower the resolution.

I'm only using 1080p, is that too high for 144hz?

Try it and see.
If you still can't go higher but you are within HBR1 spec then you can try tools like refreshlock to force a higher refresh rate.

You're right. I can only go up to 1680x1050 with 144hz on windows xp. oh well at least i can game at 144hz 1920x1080 on windows 7.

One more question please, why does my monitor display 144hz at 1920x1080p on the desktop but as soon as I switch to fullscreen directx3d mode at that resolution it can only handle 75hz? It almost sounds like a driver limitation, because on windows xp (at least for me) full screen OpenGL mode at 1920x1080 does work at 144hz. All games that use direct3d with the 14.4 drivers can only do 144hz at 1680x1050. So this is a direct3d driver problem that was never fixed for Xp? thanks. 😀

Check in- and out- game settings.
Some have their own utilities to set refresh rate, which is separate from Windows desktop.

A few times i restarted the computer on Xp and Catalyst complained (error message) about the display port cable not being able to handle the resolution or something. So I ordered a new cable from amazon (i ordered one before but i got a refund because UPS lost it). Not sure if it will make a difference though because Windows 7-64 seems to have no problems with the cable except the only issue i have is i cannot oc my card at 144hz. At 120hz and below overclocking does work however. I can oc on Xp at 144hz but can't go past 1170mhz on the core. So maybe its a cable issue.

OS = Windows XP SP3 x86

GPU : ASUS R9 280X 3GB "TOP", using Display Port to Display Port cable.
Driver : Catalyst 14.4 "pack 2" (source : LINK)

Caution 1 : CCC has separate option for forcing selected refresh rate under fullscreen (3D Refresh Rate Override option).
Caution 2 : CCC has option to hide refresh rates it thinks your monitor can't support (can by bypassed forcing all modes to be available).

I'm not sure about Catalyst (CCC), but with nVidia you most likely would have to write your own timings to get higher refresh rate on XP. This page would be helpful for those who want to set up custom timings, be it for video card, or EDID emulators.

On WinXP there is a setting for 1080p/120Hz with my Quadro, but the output is messed up. If I create a custom resolution for 1080p/120Hz using CVT-RB timing then I get a proper 120Hz output.

As for 144Hz... I don't think it would be viable. With just HBR1/HDMI 1.4 bandwidth, you need at least CVT-RBv2 to keep it within the clock limit (340MHz).

Not sure if the ability to add custom resolution is possible with consumer (Radeon/GeForce) cards. At least I know that the ability to load/lock a (modded) EDID is exclusive to workstation (FirePro/Quadro) cards.

thanks guys i bought a new cable if that doesn't work i'll have to be happy with 1680x1050 centered timing 144hz.

desktop mode works at 144hz 1920x1080

fullscreen opengl works at 144hz 1920x1080

the highest i can get d3d games to work at 144hz is 1680x1050

i can't even get d3d games to run 1920x1080 at 100hz or 120hz only 75hz works, that's why i think it might be the stock cable that is causing these issues

Edit!

I got it working with RefreshLock. Lol!